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Repair Topics / Check Engine Light-1 / Check Engine Light-2 / Check Engine Light-3 / Check Engine Light-4

Check Engine Light Question and Answers

This category contains featured questions as examples and relate to most vehicles.
 
Question: 1997 Grand Voyager 3.3 Liter mileage: 158,000. Service Engine Soon Light stays ON. Had 1 of the O2 Sensors replaced according to Repair Shop Code Scan. Light went out but came back ON and remains ON. Need to pass NYS Emissions Test soon. Are these Minivans noted for Service Engine Soon Lights? What can I do to put this light out to pass the emissions test? Thank you.

Answer: The computer code for the oxygen sensor may be caused by a lean fuel mixture not a faulty oxygen sensor. Check the fuel supply particularly the fuel filter and pump. Also, check the mass airflow sensor and check the engine intake system and hoses for vacuum leaks.



Question: 1999 Ford Explorer 4.0. Code 12, Rpm not within self test upper limit and code 14, profile ignition pick-up circuit fault. It is a distributor-less system. I have replaced the PCM, ICM module, TPS, EGR valve, spark plugs and wires, the EGR sensors test good. I'm at a loss as where to go to correct these two faults.

Answer: Try replacing the pickup coil and the ignition coil.


Question: 2001 Mazda Millennia mileage: 72,000. Yesterday, I got a check engine light. The local AutoZone diagnosed the P0173 code to be "fuel trim". They couldn't elaborate on what that might mean. I just bought the car and to my knowledge the injectors haven't been cleaned. I did have to replace an O2 sensor a month ago. I just read on the web that some cars require a mechanic to disconnect the battery when changing the O2 sensor to reset the long term fuel trim. I remember having to reset the radio after their work. Is it the injectors? What am I missing?

Answer: The code you mentioned is a general code for problems with the fuel injection system. It could mean that the fuel pressure regulator is faulty, or something is wrong with the fuel pump or the fuel injectors.


Question: 1999 Toyota Tercel 4 cyl mileage: 91,000.  Dear Bob and Ken: My problem concerns my 1999 Toyota Tercel, 91000 miles, 4-speed manual transmission, most recent oil change was about 1800 miles ago, and no major repairs since purchasing the car at 40000 miles.   I recently made a 1600-mile trip from Virginia to Colorado; I had the oil changed, fluids topped-off, and air filter replaced.   Additionally, I had an emissions inspection done a few weeks before, and the results were excellent.  Approximately half way through the trip and some very bumpy interstate driving in Arkansas and Oklahoma, my "Engine" light came on.  I pulled over immediately to check under the engine, checked the oil level, belts, hoses, etc. and found no noticeable irregularities, except that the overflow container for the radiator fluid was empty.  There was still plenty of fluid in the radiator itself, but I replaced the fluid/water mixture anyway.  I noticed no odd smells or drivability difficulties, so I continued driving.  I stopped overnight and the following morning, I checked my owner’s manual and it said that this light comes on due to a problem with the engine's electrical system.  Being that the roads were rough, I suspected maybe a fuse had been knocked out, so I removed, inspected, then replaced all of the fuses.  I started the car and the engine light was off.  I continued driving, but after about 6 hours of interstate driving (70-80 mph) the light came on again.   Still, I did not notice any smells, sounds, or drivability problems.  I continued to drive as I was in the middle of nowhere and arrived in Colorado, still with the engine light on.  I spoke with a technician about this before and his recommendation was that the oxygen sensor could be the problem.  I have researched the function and possible problems of the O2 sensor and it seems like if that were the culprit, my exhaust would smell like "rotten eggs" OR produce a black smoke (depending on lean or rich mixture).  Is this correct?  Or could the sensor be malfunctioning WITHOUT a real problem with the mixture?  What type of problems could develop with continued driving?  Could there be another cause to the engine light coming on?   Is there some way to check the sensor myself without having to take to a mechanic?  Could the missing radiator fluid have caused something to go wrong (I have noticed no leaks in the overflow tank since)?  Could the change in altitude cause something?  I apologize for the length of this, but wanted to make sure to get all of the information here.  Thank you in advance for your help!

Answer: You probably do have a faulty oxygen sensor.  With 91000 miles on your car, it would be good practice to replace it anyway.  If your problem persists, then scan the computer for fault codes.   Oxygen sensors go out of range at times, but still work.


Question: 1994 Honda Civic mileage: 187,000.  Check engine light continues to come on periodically. When the light is on the overdrive doesn't engage.  I tested the car with light on and off.  I replaced the oxygen sensor, fuel filter and had it checked by a mechanics computer code system.  The trouble code 1 (oxygen content) circuit continues even though I have done all the Haynes manual suggests.  I called the dealer and they are stumped also.  The only thing I can think of next is the Engine control module, however that part is $1250.  Car runs excellent with the light on or off.  What do you think is the next step?

Answer: Check the air diverter valve that puts fresh air into the exhaust system, as it may not be functioning properly.



Question: 1999 Ford Taurus Station Wagon  mileage: 130,000.   My mechanic doesn't seem to know what the problem is with my car so I have come to ask you. The engine light keeps coming on.  It doesn't stay on long enough to register on the computer.   Maybe 10 seconds at most.  Some time it just barely flashes.  It will go off if I accelerate, brake, or just wait.  The engine does seem bogged down sometimes when the light is on, but not all the time.  Another thing, (I don't know if this is related or not) sometimes the signal lights don't work.  I can go for months where it is fine then a day or a week where they don't work.  The heater also doesn't work if the signal lights are not working.  I know those two things are related, but the engine light might have nothing to do with them.  Please help!   If there is, more information that you need just let me know.  Thank you!  Jessica

Answer: The “check engine” light will “light” when there is a malfunction in the engine management system.  The fault code is then stored in the computer.  The computer must be scanned to retrieve these stored faults to pinpoint the malfunctioning component.  Also, take a 12-volt test light and check out the power to the heater and turn signals when they are not working.


Question: 1996 Plymouth Grand Voyager 3.0 mileage: 177,000.  Bob and Ken, Great web site.  First time caller.   Quick question.  A few thousand miles back 75 or 80K the maintenance required light on the dashboard illuminated.  My local mechanic said that Plymouth set those to go off based upon mileage on this particular vehicle.   He reset the light.  Guess what?  It comes back on again recently.  Stupid me did not ask for the reset steps.  What are the procedures to reset that light?  I hate to go buy a $50 manual for a van I plan to sell in a couple of months.  Or, worse yet, pay a Plymouth dealer $200 to put the light out.  BY the way, the van does not have any problems at all.  Gas mileage is still in the upper 20s in the city and in the mid 30s on the highway.  Oh yea the transmission was changed out (standard for these vans) at 88K.  Thanks for the tip.  Pat

Answer: However, the “check engine” light will “light” when there is a malfunction in the engine management system.  The fault code is then stored in the computer.  The computer must be scanned to retrieve these stored faults to pinpoint the malfunctioning component.  Because the check engine light indicates something is wrong, a trip to you neighborhood automobile service center sooner rather than later is recommended.


Question: 1993 Isuzu Trooper 3.2 mileage: 97,000.  My service engine light was always coming on but nothing appeared wrong with the vehicle.  My gas pump and oxygen sensor had just been replaced, my oil changed and my charging system checked.   My mechanic said that it appeared that I needed to replace my modulator but rigged it so it would work okay for a while.  Will this hurt the vehicle?  How important is this modulator?

Answer:  Your car is equipped with a computer controlled engine management system.  An independent auto service center can scan your computer for fault or error codes.  The information should pinpoint the malfunctioning components.   If a major tune-up has not been done recently, this could be the cause of your problem.  Replace the spark plugs, plug wires, fuel and air filters, etc.  Also, replace the oxygen sensor.  In addition, service the fuel injection system.  Clean the carbon deposits from the throttle bore and idle passages.



Question: 1998 Chevrolet Lumina mileage: 85,000.  If the car is warmed up and I'm at highway speed, then suddenly let off the gas, the service engine soon indicator will light.  It is generating an EGR code (32, I believe).  The light generally stays on until I shut off the engine.  This happens more often when the outside temperature is at least roughly 40 degrees.  However, this does not have a big effect.  I have taken the digital EGR valve off and none of the valves is sticking. 

Answer:  Your EGR valve may not be operating properly and may need replacement.



Question: 1999 Jeep Cherokee Sport ST 6 mileage: 83,000.  On a trip check, engine light came on 40 miles into trip.  I pulled off and checked fluids, all ok.  Vehicle cooled down, all gauges looked ok.  Continue trip, another 40 miles motor acts as if it will cut off.  Pull off once again, let cool down.  Vehicle starts immediately.  Runs perfect for another 40 miles, does same thing.  I notice that I cannot set cruise control.  I have replaced fuel filter, spark plugs, plug wires, distributor cap, rotor button, and ignition coil.  Still have problem.   Next move is EGR valve.  Call Jeep shop to order part, they say I haven't an EGR valve in their books, must be something else?  Take to shop, they read codes, nothing out of the ordinary, all sensors are performing correctly.   They cannot recreate problem.  They return to me unrepaired and still can not set cruise control.  What gives?  EGR or oxygen sensors?  I would gratefully appreciate any insight you may have on my problem.  Thank you.

Answer:   The “check engine” light will “light” when there is a malfunction in the engine management system.  The fault code is then stored in the computer.  The computer must be scanned to retrieve these stored faults to pinpoint the malfunctioning component.  Because the check engine light indicates something is wrong, a trip to you neighborhood automobile service center sooner rather than later is recommended.  Try another service center; the first one appears it have missed it.



Question: 1999 Mercury Sable mileage: 89,000.  The service engine light is on, had it checked and got a code 41-oxygen sensor.  Need to know if it is the front or back that needs to be replaced.  Or if I should replace both.  Thank you.

Answer:  Replace both Oxygen sensors.  You may have to have your computer scanned again to reset the light.


Question: 1990 Plymouth Voyager mileage: 183,000.  Just replaced the 02 sensor, but we are unable to turn off the maintenance-required light.  Any suggestions?

Answer:   Try disconnecting the negative battery for approximately 15 seconds and reconnecting.  If the light is still on, have the engine computer scanned for fault codes.


Question: 1999 Dodge Grand Caravan 3.3 mileage: 72,000.  I read the questions for Tuesday on the  dodge caravan.  My check engine light also comes on.  What I want to know, if you can be more specific, in your opinion, what are the possibilities that can make your engine light come on.  I have taken my car to mechanics, and they tell me everything that is wrong with my car that really isn't. It's hard to find an honest mechanic.  I want to make sure I know what they are talking about, and that they are not lying to me.

Answer:  There are a number of things that can malfunction and cause the check engine light to come on.  We are sorry to hear you are getting the run-a-round with your car repairs.  Talk with friends and neighbors to locate a professional auto mechanic you can trust.  Have him/her inspect the car giving him/her the same information you gave us.


Question: 1999 Mitsubishi Lancer mileage: 70,900.  This morning, my check engine light came on and stayed on.  I don't know what's wrong with it.  This is my first car.  I tried to take it to a repair shop, but was told to take it to a Mitsubishi dealership.  Do dealerships fix cars also or should I just take it to a different repair shop?

Answer:  Try a different repair shop that has the proper equipment.  The “check engine” light will “light” when there is a malfunction in the engine management system.  The fault code is then stored in the computer.  The computer must be scanned to retrieve these stored faults to pinpoint the malfunctioning component.   Because the check engine light indicates something is wrong, a trip to you neighborhood automobile service center sooner rather than later is recommended.

Repair Topics / Check Engine Light-1 / Check Engine Light-2 / Check Engine Light-3 / Check Engine Light-4

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