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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
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/ Check Engine Light-2
/ Check Engine Light-3
/ Check Engine Light-4
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