Saturday, September 30, 2006

Instrument panel lights go out on 1999 Toyota Camry with 3.0L engine: no engine code

Question:

I have an intermittent problem on my dash panel lights. It goes out from time to time and when it does, the power window also won't work. Everytime this happens, I have to change the panel fuse under the left side of the dash. There is no code when I had it scanned. How do I check this?
ATS Advisor:

If you open up your rear trunk; on the left side hinge, you will see a wiring harness that supplies ground to your lights including the power windows and dash panel. Take the wiring harness loom apart and check the wires. Most of the time, some of these wires will brake causing this problem. This is very common on these models.

ATS Tips:

If you use the ATS wiring diagram, you can see clearly the composition of that wiring harness and the colors of the wires used for grounding.

Friday, September 29, 2006

Cruise control not working on 1999 VW Passat with 1.8 engine: No engine code




Question:

My cruise control quit on me 3 days ago and there are no codes. I checked all the vacuum lines and they are all fine. When I checked the power supply from the transmission control module located at the lower side of the dash by the defroster duct, there is none. How do this system works? Can I do this myself?

ATS Advisor:

If you are talking about the green red wire from the trany control module, that is supposed to be your power supply wire to your cruise control switch. However, it will only come on as soon as you put the trany in gear. It will stop when you shut off the engine or step on the brake pedal. Most of the time, this module goes because of cracking in the electrical joints in the terminals inside the module. If you call the dealer right now, they stock it all the time. You should be able to change the module yourself but don't forget to disconnect the battery when working on electric parts.

ATS Tips:

The above cruise system applies only for automatic transmission. For manual trany, power comes from the clutch switch but it does not work on the first gear.

For wiring diagrams to help you find the wire colors to all components, please contact ATS.

Thursday, September 28, 2006

Code P0172 on fuel mixture for 2000 Volkswagen with 1.8 Turbocharged engines


Question:

This code came up on dash P0172 system mixture too rich and as per ATS past newsletters, I changed the mass air flow sensor but the code remains. I tested it for vacuum leak but cannot find any. The engine ran fine but won't pass emission. Any suggestion?

ATS Advisor:

If this is a regular fuel injected engine, I would recommend checking the fuel regulator which could have a ruptured diaphragm. However, since this is turbo charged, it is very common for the vacuum connection going to it to leak. It's made of plastic and called a suction jet pump which is similar to a pcv valve. This part usually fails and will cause a vacuum leak when the engine is boosted by the turbo. The computer will make up for it by injecting more fuel causing the rich condition. Check and repair this leak and this should fix it.

ATS Tips:

Contact ATS if you need the vacuum diagram for these turbo vacuum lines.
The vacuum hoses are expensive and must be handled with extreme care

Wednesday, September 27, 2006

Oil pressure gage not working on 2000 Ford Explorer with 4.0L engine: No codes




Question:

What could cause my oil pressure gage not to work momentarily when stated cold? This happens for 30-40 seconds but sometimes could last up to 1-2 minutes. However, after the engine has warmed up, the gage works great until the engine is shut down and gets cold again. Some friends said that the sending unit is defective but I need your input first.


ATS Advisor:

The normal mechanical oil pressure gage usually shoots up in reading when started cold using the regular type sending unit. However, Ford has used a different sending unit which has caused a lot of problems such as yours. Regular sending units usually work by pressure difference being monitored but this type of sending unit works like a "switch" instead. An updated sending unit is available from Ford to prevent this problem.

ATS Tip:

Make sure the engine is mechanically sound by checking the actual oil pressure with your own oil pressure gage tester. Do this before installing the new updated sending unit.

Tuesday, September 26, 2006

Rear power window only works in up position but not down on 1999 Malibu: No codes




Question:

My rear right power window is only working when in up direction but not going down. I opened up the door panel and it seems the wires to motor are shorted because both of them have power. When I removed the motor and bench tested it, the down position would work if I reverse the ground to power supplies. Is this a switch problem? How do I check it?

ATS Advisor:

The power window works thru your master switch at the drivers door and also at the right door itself. It is done by reversing the polarity of the motor windings which is the job of the master switch. On your master switch, there are 2 wires coming out to your right door switch: light green and purple wires. When in up position the light green wire is the ground and on down, it's the purple wire. This is done thru the electronics module inside the master switch. When applying in either position and both of these wires became ground at the same time, then the master switch is defective (same if these wires are both 12 volts as in your case). However if the ground supply is reversing to either wires, then the problem is the rear door switch.

ATS Tip:

To understand this fully, contact ATS so you can get a wiring diagram describing the colors of the wires and their locations.

Rear power window only works in up position but not down on 1999 Malibu: No codes

Question:

My rear right power window is only working when in up direction but not going down. I opened up the door panel and it seems the wires to motor are shorted because both of them have power. When I removed the motor and bench tested it, the down position would work if I reverse the ground to power supplies. Is this a switch problem? How do I check it?

ATS Advisor:

The power window works thru your master switch at the drivers door and also at the right door itself. It is done by reversing the polarity of the motor windings which is the job of the master switch. On your master switch, there are 2 wires coming out to your right door switch: light green and purple wires. When in up position the light green wire is the ground and on down, it's the purple wire. This is done thru the electronics module inside the master switch. When applying in either position and both of these wires became ground at the same time, then the master switch is defective (same if these wires are both 12 volts as in your case). However if the ground supply is reversing to either wires, then the problem is the door switch.

ATS Tip:

To understand this fully, contact ATS so you can get a wiring diagram describing the colors of the wires and their locations.

Rear power window only works in up position but not down on 1999 Malibu: No codes

Question:

My rear right power window is only working when in up direction but not going down. I opened up the door panel and it seems the wires to motor are shorted because both of them have power. When I removed the motor and bench tested it, the down position would work if I reverse the ground to power supplies. Is this a switch problem? How do I check it?

ATS Advisor:

The power window works thru your master switch at the drivers door and also at the right door itself. It is done by reversing the polarity of the motor windings which is the job of the master switch. On your master switch, there are 2 wires coming out to your right door switch: light green and purple wires. When in up position the light green wire is the ground and on down, it's the purple wire. This is done thru the electronics module inside the master switch. When applying in either position and both of these wires became ground at the same time, then the master switch is defective (same if these wires are both 12 volts as in your case). However if the ground supply is reversing to either wires, then the problem is the door switch.


ATS Tip:

To understand this fully, contact ATS so you can get a wiring diagram describing the colors of the wires and their locations.

Monday, September 25, 2006

Fuel gage reading wrong for 1999 Ford Taurus: No codes

Question:

My fuel gage does not work properly and fluctuates between 1/4 to 1/2 all the time even if the tank is full. Over the weekend, I changed the fuel sending unit inside the fuel tank but it's still the same. Some friends are telling me to change the instrument cluster but I am not sure. Can you help?

ATS Advisor:

It's good you did not follow your friends because you would be wasting your time. There is small black box behind your radio near the glove compartment and this part is usually the culprit. This part is called a flex module and connects to your fuel gage in the instrument panel and usually goes. This is a common problem and ford stock them all the time.

ATS Tip:

To get a wiring diagram so you can locate this part, please contact ATS if you are a member.

Sunday, September 24, 2006

Trany won't engage in either drive or reverse for 1999 Volkswagen Passat with 1.8L engine: No codes



Question:

How do you check if the trany is OK or not quickly without going to a garage?

ATS Advisor:

You can actually do this by measuring your oil level at the trany dipstick tube. All you do is compare the level when engine is off and after it has started. If the trany is OK, the level should go down at least 1/4 of an inch when engine is started. This shows that the trany pump is working inside, otherwise if no movement, trany is probably damaged and needs further testing by a trany garage.

ATS Quick Tips:

If trany has no dipstick, you can also feel the hose connection of the trany oil cooler. If oil is circulating after starting, the hose will harden as soon as the engine is started (or hook up your own oil pressure gage teed to the oil coller hose).

Be careful when going underneath your trany or contact ATS for proper procedure.

Saturday, September 23, 2006

P0123 TPS code on 1998 Jeep Cherokee with 4.0L engine

Question:

My check engine light code p0123 keeps coming back despite replacing these parts: tps sensor (2 times in a week), ecm (engine computer) 2 times using a used ones from salvage yard. after I drove it for a few minutes, the code always came back. Also, if I probed my TPS ground wire, I get a high battery voltage. I am losing out of options for this problem, what do I do?

ATS Adviser:

If you look at the ground wire of your tps (3rd wire and brown yellow in color), that wire is also the ground connections for other components including your ecm. You can disconnect the ecm and re-test your ground tps voltage and see if the reading drops. if not, try to unplug the horn relay in the junction box and check if the tps ground will go down. If it does, it means the horn circuit is sending voltage (shorted) tps ground via the clockspring located under the steering wheel.

ATS Tip:
For more details, get a wiring diagram from ATS.

Friday, September 22, 2006

P0400 code on egr system for 1999 Nissan Maxima with 3.0L engine.

Question:

I have this P0400 EGR malfunction in this vehicle and following ATS past newsletters, I have serviced the egr valve and verified integrity of the vacuum hoses and blew the egr passages. However, after resetting the code, it came back after 3 days of driving. Did I miss anything on fixing this code? Is it possible that the ecm (engine computer) itself is no good?

ATS Adviser:

Your ecm should be good but there is a possibility that you have not really cleaned the egr passages thoroughly because this job needs the removal of the top plenum in your engine. There is a tube there that contains the egr signal to the ecm to monitor the egr system. Anytime, that passage is blocked, your ecm will store an egr fault code. You can test this by running your engine at idle and lift with your finger the egr pintle shaft of the egr valve. This should make your engine quit, otherwise, the passage itself is clogged.

ATS Tip:

While you are doing this, you can also check the integrity of the egr valve which could be stuck closed including the egr temperature sensor voltage. Finally, a weak battery can also cause this code which is very common. Please contact ATS for further details.

Thursday, September 21, 2006

Heater noise on 2000 Silverado when rpm is speed up: No engine codes

Question:

It is starting to get cold and my heater is making a funny noise every time I rev up the engine speed. I tried flushing the coolant system but it did not make any difference. The parts store told me that I need a new heater core but I want to run this by you before buying it.

ATS Advisor:

GM trucks like yours have this problem for a while and this is caused by a strong flow of coolant inside your heater core. To eliminate this, there is a rubber restrictor in the inlet side of the heater hose installed in it. This restrictor or orifice might have broken and must be replaced. Make sure to check this and replace if necessary.

ATS Tip:

While you are doing this, check all your hoses for connections and see that the hoses are not swelling and properly routed away from exhaust. When done, do a pressure test on the coolant to make sure every thing is tight and secure including the elimination of air in the system.(this is discussed in ATS past newsletters).

Wednesday, September 20, 2006

P0402 EGR code on 2001 Expedition with 4.6L engine



Question:

This code P0402 -EGR flow high, came on the other day on my vehicle and when I introduced vacuum to the egr valve port at idle, the engine quit which tells me that the valve is OK. The engine seems to run OK except this nagging light so I reset the code but it came back. Is there a common fix for this code?

ATS Adviser:

There is a common fix for this and most of the time it is to replace the DPFE sensor. This sensor looks like a small box with 2 ports coming from the exhaust. The sensor is located between the valve cove and throttle body with tubes running from it. This sensor measures the exhaust back pressure when the EGR valve is activated. The passages (tubes) for this sensor can get cracked and leak to trip the code but there has been a lot of failure on the sensor itself. Also, if the tube has a build up of carbon and restrict the flow, the code can be set too. To check, measure the signal voltage of the sensor using a wiring diagram. Max reading is about 0.9 volt and any reading higher means you have to replace the sensor.

ATS Tip:

Wiring diagram is available at ATS if you are a member.

Tuesday, September 19, 2006

P0170 and P0173 adaptation codes on 1998 Mercedes Benz ML320 with 3.2 engines.




Question:

I have these codes P0170- self adaptation out of limits right bank and P0173-self adaptation out of limits left bank and as per your ATS lessons, I checked for vacuum leak but found none. A tune up was also done just a week ago but this check engine light keeps coming back. I am out of my wits on this...how do I fix these codes without going to the dealer?

ATS Adviser:

These codes are very common on this type of vehicle especially on tthe 98-99 models and is caused by a defective air mass sensor. To check, try servicing the mass sensor as per ATS past newsletters and reset the code by touching the battery terminals for a few minutes. You can then go for a road test and if there is changed in the mill light, replace the mass sensor next time it occurs (some shops are actually changing the mass sensor right away if they see these codes).

ATS tip:

Make sure your fuel pressure is up to specification before replacing the mass sensor.
To get ATS email assistance 7 days a week, contact ATS.

Monday, September 18, 2006

2002 Dodge Caravan high beam headlight does not work : No Codes


Question:

My headlight's high beam does not work intermittently from time to time. All my gages in the dash panel are OK including all the rest of the lights like fog lights and interior lights. No codes came out after scanning it and I am thinking of replacing the multi-function switch from the steering wheel but I am not sure if this is the right approach. Can you help?

ATS Adviser:

The way your lighting system works, there are 3 major lighting components namely the multifunction switch, body control module and the intelligent power module (IPM). Since the most of your lights are working except the high beam, your most likely culprit is the IPM which direct supply the power to your headlights.Using a wiring diagram, the power, ground and pci bus voltage on it can be checked and verified. If it is not within limits, replace the same.

ATS Tip:

ATS will provide the correct voltage readings for the IPM including detailed instructions on how to test the lighting circuit.

Sunday, September 17, 2006

P0456 Code EVAP leak for 2001 Jeep Wrangler with 4.0L engine

Question:

I have this code P0456- evaporative vacuum leak and I have changed the fuel tank cap but keeps getting this code. I also tried to check all the evaporative vacuum lines for cracks and leak but cannot see anything abnormal. How do I test this code?

ATS Adviser:


You can actually do a vacuum test on this evaporative system by activating your leak detection pump (LDP) to seal the system. All you do is supply your own ground to the LDP signal wire and disconnect the evaporative purge solenoid wires. Remember to undo also the vacuum hose supply hose going to it and install a hand held vacuum gage to the 2nd hose. This will test your LDP and all hoses if it has a vacuum leak or not.

ATS Tip:

ATS will supply you the vacuum and wiring diagram if you are an ATS member.

Don't forget to reset the code after the fix.

Saturday, September 16, 2006

2000 Toyota Camry ignition key with immobilizer has no start: No codes

Question:

I lost the ignition key on this car and I don't have a spare. Previous owner told me that this car's engine has an immobilizer and it needs a new ecu (engine computer) if I lost the key. Is there a way to bypass the immobilizer?

ATS Adviser:

There is no way to bypass this immobilizer and the only solution is to get a new ecu and have it programmed with a new set of keys. On a positive note, Toyota will provide you with a new ecu free of charge and you just have to call your nearest dealer to confirm this. Some dealers might refuse your request if they don't know if such practice exists and all you need to do is call Toyota head office to confirm.

ATS Tips:

Ignition immobilizer is a security system used by Toyota to enable your engine to shut down in case of theft. It does it by killing your engine injectors.

Starting 2002, Toyota can re-program your old ecu without replacing it when you lose your ignition key. Just ask them and give the car's serial number.

Friday, September 15, 2006

Battery drain on 2002 GM Silverado Truck: No Codes


Question:

My battery loses charged if I leave the truck parked for over 3 days. I believe this battery is still the original one from the dealer but I am not sure because I am the 2nd owner. However, every time I boosted it, it seems OK for the rest of the day. How do I check it?

ATS Advisor:


Battery can be checked visually by reading the info on the paper glued to it and you can compare the date the battery was made against the vehicle date of manufacture. This will tell you if it comes with the truck. You can also test it by putting a voltmeter between the vehicle metal grounds against battery negative cable (remove it). With all doors shut and accessories off, the maximum reading should not exceed 0.250 volt. Higher than this means you have a drain from one of your wiring or engine computer modules. Finally, if the battery has a sight glass, make sure it is a solid green color which indicates that the battery is fully charged.

ATS Tips:

IF you have a drain, get a wiring diagram from ATS to trace the short or unplug your fuse one at a time until the drain goes away.

If you have no drain (lower than 0.250 volt), replace the battery.

You have to wait at least 45 minutes when measuring the drain. Some of this vehicle has a timer inside to automatically remove the load. Contact ATS for more detailed info.

Thursday, September 14, 2006

Dash panel lights and accessories coming on and off when raining for 1998 Expedition: No Codes


Question:

Why would my dash panel gages, lights and accessories devices come on and of everytime it rains? Sometimes, the blower motor would even run by itself after I removed the key. I also hear relays clicking all the time and I checked all the ground connections but I got the same result. Help!

ATS Adviser:

If your windshield had been replaced recently, chances are the windshield is leaking. This would allow rain water to drip to the fuse block and the GEM (Generic Electronic Module) module which are located below. When that happens, it will create a short in your wirings and the GEM module causing this erratic behavior. Your best strategy is to remove the windshield and re-seal it again. At the same time, replace the GEM module and the fuse block.

ATS tip:

Ask your Ford dealer to sell you an upgraded GEM module (another name for this is the BCM) and make sure it is programmed for your vehicle. For further technical assistance thru email, contact ATS.

Wednesday, September 13, 2006

P1143 code for 2000 Jetta with 2.0 L engine but vehicle has no performance problem?

Question:

This code P1143-ecm load calculation cross check upper limit exceeded came on my scanner when the mil light appeared. There is no noticeable change in engine performance but I hate to see the mil light. This happened after my mechanic changed the mass sensor yesterday. How do I fix this?

ATS Advisor:

That code will come whenever the mass sensor that was replaced is not the correct one. Ask your mechanic to get the correct one and have it replaced again.

Tips:

To prevent ordering the wrong mass sensor, always give the engine code to match the part number of your mass sensor.

Reset the code after replacing the mass sensor.

Tuesday, September 12, 2006

P1128 engine lean code for 2000 Volkswagen Cabrio with 2.0L engine


Question:

This vehicle has this code P1128-bank1 lean code. I have tested the engine for vacuum leak using ATS tips and no leak was found. Using my fuel pressure gage the fuel pump pressure was also checked OK. I also did a quick tune up like changing the spark plugs, wires and fuel filter to no avail. In your ATS tips, you mentioned the failure of mass sensor causing this, is this the case here?

ATS Advisor:

You are correct to suspect the mass sensor is the culprit. As a matter of fact you can call the dealer and you will find they stock it a lot. The sensor fails because of oil contamination being induced in the intake. Don't even bother cleaning it but replace it.

Tips:
Once the mass sensor is replace, reset the code by touching both batt together for a few minutes.

While you are at it, replace your pcv valve to prevent contamination.

Monday, September 11, 2006

Heater blower motor does not work on 2000 Durango: No codes


Question:

My heater blower motor suddenly quit when it was turned on. However, if a direct battery power and ground are fed to it, the high speed works. There is no code when scanned but I cannot find the relay connected to it. Suggestion?

ATS Advisor:

When you jumped the power and ground supplies and the heater motor works, it means the blower motor is OK. The motor is controlled by a resistor to vary the speed. It is usually located below the blower housing and that is a common cause of failure.

TIP:

Before you replace the resistor, make sure the ground wires are secure and not corroded. Contact ATS if you need assistance.

Sunday, September 10, 2006

Speedometer not working on 2000 Subaru Legacy: NO codes

Question:

I have replaced the speed sensor of the speedo system located in the transaxle because the speedometer won't work. When ordering the speed sensor, I used the original equipment (OEM) from the dealer. After the replacement, the speedo works for a week but started to quit intermittently. Did I get a defective sensor? How do I know?

ATS Adviser:

If you used the wrong part, your speedo will probably won't work on day 1 but since you got it working for a week, most likely it is OK. If it is acting up again, try checking for loose connections that might cause this problem. However, if the symptom continues, consider replacing the speedo head. This head is known to fail often and if you call the dealer, they stock it all the time.

Note:

For more detailed instruction for the replacement/testing of the speedo head, please contact ATS.

Friday, September 08, 2006

P0420 and P0172 Codes for 1997 Chevy Astro with 4.3L engine

Question:

This van has codes P0420-low catalytic efficiency and P0172-rich mixture bank 2. The fuel pressure is within limits and has no vacuum leak. The pcv valve was taken out and the reading to the downstream oxygen sensor did not change. Removing the dipstick tube did not reveal any blowby. What can I do before I bring this to garage?

ATS Adviser:

On this engine, you have 3 oxygen sensors. Two of them are in the exhaust manifold(upstream) and the last one is at after the catalytic converter or CAT(downstream). Try monitoring the 2 upstream sensors first by introducing vacuum leak and check the signal on the sensors. If the reading are not going down when you do this, replace the 2 upstream sensors. Reset the code after replacement and see if the down stream reading will now improve.

Note:

The 2 upstream sensors are used to monitor the engine whereas the last one is used to monitor the CAT. Contact ATS to get more help if the code remains.

Thursday, September 07, 2006

P0128 thermostat code for 2002 Ford Focus with 2.0L engine


Question:

This engine has a P0128 code-coolant temperature setting below thermostat-regulated parameter; engine rpm is rough every time the light is on. Do I have to change the thermostat on this?

Code Description:
This code is very common on this engine if the thermostat is stuck or partially stuck open. To check make sure the radiator cap is good or replace it if possible. If the light still shows up, replace the thermostat.

Repair Tip:

After replacing the thermostat, make sure to reset the engine code. Should the code returns, contact ATS for further assistance.

Wednesday, September 06, 2006

P1128 code for 1999 Jetta with 2.0L engine


Question:

I got this code P1128 -long term fuel trim lean that keeps coming back even after I reset the code. An inspection and voltage measurement of the oxygen sensor looked OK and there is no vacuum leak detected. The fuel filter was also replaced but the code remained. What do I look for to fix this code?

ATS Advisor:

The most common problem for this code is the mass sensor if you believe it! Located in the air cleaner ducting, its worst enemy is poorly maintained air filter that collects dirt and contaminates the mass sensor wire elements. See ATS past newsletters for corrective action.

Repair Technique:

When checking mass sensor, check also for signs of oil contamination in the mass sensor elements that can easily corrupt the mass sensor signal. If possible, put a new one since 9 out of ten calls for the mass sensor replacement.

Tuesday, September 05, 2006

Chrysler Intrepid 3.5L engines with misfiring problems.


Problem:

This engine misfires all the time and it happens at all speed whether the engine is cold or hot. It has direct ignition and has no spark plug wires. Instead, it has coil wire boots fed on top of each cylinder. What is the quickest way to check this misfiring?

Basic Concept:

On this type of engine, the heat build up in the engine will cause a breakdown in the coil wire boots that will arch and cause the misfire. Try unplugging the coil wire boots and have a look at the rubber insulation. If you see a brown spot, it shows the boot is arching.

Repair Strategy:

After pulling out the coil wire boots and you see even one boot arching, replace the coil wire boots as a set. (if one goes, the rest is not far behind). For more details in the repair procedures, please contact ATS.

Monday, September 04, 2006

Horn is on all the time on 2001 Dodge Truck R1500 and there are no codes.

Question:

Horn will not stop but will stop if you pull the horn relay fuse or disconnect the clock spring wire in the steering wheel. Any suggestion?

Basic Theory:

As shown in ATS wiring diagram, the horn relay gets its ground starting from the horn switch that you press then thru the clock spring black red wire that activates the horn relay coil so it can send 12 volts to the horn located in the front of the vehicle. Most likely, the ground wire is shorting out making the horn come on in uncontrolled fashion.

Repair Technique:

Check the steering column black red wire that feeds the clock spring and if possible, remove the steering wheel cover to access the clock spring. If your truck has an airbag, make sure to disconnect the negative battery cable. After this, you are supposed to wait at least a minute to prevent the accidental duplication of the air bag.

Sunday, September 03, 2006

P0172 code from 2000 Lexus RX 300 with 3.0L engine

Question:

The check engine light in the dash is always on and a code of P0172-bank1 running rich was taken from the scanner. The oxygen sensor tested OK and there are no signs of vacuum leak when I tested it. I am now tempted to remove the engine top plenum so I can test the injectors and ignition coils. Before I do this, is there a common fix for this code?

ATS Advisor:

Whether your engine is running rich or lean, almost 95% of this engine code comes from contaminated mass sensor. Take it out and service the wire elements. This sensor usually goes in this vehicle especially if the air filter is not serviced regularly. If possible, replace the sensor and reset the code. ATS provides instructions in servicing the mass sensor including the wiring diagram.

Saturday, September 02, 2006

P0300 code for 2000 Silverado with 4.8L engine


Symptoms:

P0300 code-random misfire after an engine computer scan. Performed chemical tune up for top end, swap ignition coils and injectors including tune up but bank 1 cylinders still showing code of misfire. Could this be another catalytic converter problem?

Basic Concept:

It looks like this is a catalytic converter (CAT) failure if misfiring is concentrated in just one bank. Again this can be tested by a vacuum gage hooked up at the exhaust manifold of bank 1 as in previous blog.

Repair Strategy:

Another test that can be done on bank 1 CAT is to measure the voltage of the oxygen sensor located after the CAT. Normally, the signal voltage will fluctuate from 0.4 volt to 0.7 volt. If the reading is not around this range, the CAT is definitely bad. For more details in testing the CAT including the wiring diagram of the oxygen sensor wires, please contact ATS.

Friday, September 01, 2006

Code P0401 on 2000 Ford WindStar with 3.8L engine

Symptoms:

Check engine light on all the time with code P0401-Insufficient EGR flow. When checking the DPFE sensor, the signal voltage was stuck whether the engine was in idle or revved up. If you apply vacuum to the EGR valve port, it will kill the engine.

Basic Concept:

The DPFE sensor signal voltage reading should change when vacuum is applied to your EGR valve port using a hand held vacuum pump. Also, take a closer look at the sensor connections for blockage or cracks that must be corrected in order for the sensor to work properly.

Repair Strategy:

Call your local Ford dealer and submit your serial (VIN) number. On some of these engine models, they will give a warranty of this DPFE sensor that has a high rate of failure. Otherwise, using a vacuum diagram supplied by ATS, double check all the vacuum connections to the DPFE before replacing it. Then reset the code before road testing the vehicle to verify the code.