Check Engine Light

I have a 2002 caviler with the check engine light on .I have had it reset several time but will come back on within one week,

The CEL comes on because the on board diagnostics is sensing a problem. There are hundreds of causes for the CEL, some can be totally ignored (in that they won't cause a worse problem); others should be addressed or you could end up stranded roadside. Some, if not addressed will cause lower gas mileage, and soon you'll pay more in gas than the cost of the repair (and still have that annoying light on).

If you pay a mechanic to diagnose and fix the problem, he should reset the CEL.

You could stop by an auto parts store (AutoZone, Kragen) and have them scan the code and reset it. Ask if it's free before they do it.

If like many Subaru owners, you have something other to do on a daily basis than check and reset the CEL, you could buy an OBDII scanner ($50-$150) to (check the code) and reset the light manually. My Forester light comes on about 3 times per year, usually with a new problem that is never less than $250.

In my experience, ultimately, you want to sell the Subaru.

Same thing.

More than likely the heater burned out in the B1 S1 O2 sensor. First locate the B1 S1 O2 sensor, it would be the one threaded into the exhaust pipe directly behind the bank of cylinders that contain the number one cylinder. Inspect the wiring leading to it looking for damage/cuts in the wiring. If the wiring looks good, disconnect the sensor from the vehicle harness, cut the wires off of the bad sensor, slip a 7/8" box wrench over the sensor and remove it by turning counterclockwise. Install the new sensor using an 7/8" open end wrench and tighten as you would a spark plug. Plug the new sensor into the vehicle harness and your done.

To turn off a heater light, locate the power switch or thermostat control on the heater itself. If it’s an electric heater, you may also need to unplug it from the wall outlet. For central heating systems, adjust the thermostat to the off position. Always ensure that the heater is safely powered down before performing maintenance or cleaning.

Check the oil level in the car.

The rainbow is a sign of the covenant that God made with Noah and his sons and their descendants, that there would never again become a flood to destory all flesh Genesis 9:8-17

Trouble code P0440 means: EVAP System No Flow During Purge

on my 05 mercedes c class. the light says

engine oil level reduce oil level. what does this mean?

Similar thing happened to me. It was the oxygen sensor that went.

They really can mean anything.. if your car is 96 or newer it has a scan port, just plug in a scanner and see what codes aren't complete

i have replaced the plugs and wires and my service engine light comes again in 2004 land rover discovery

you have a leak on the sending unit (o-ring usually after a pump replacement) or a hose to the canister EVAP system

No idea to be honest, but i have a 95 Corsica with a similar problem that will turn the Service engine light on after a while of driving highway speeds, or after reaching highway speeds and slowing down again. After getting the code read i found out it was for the EGR valve sensor. Basically meaning that its positioning fine at normal in town driving but not working as it should at higher speeds.

Again i can't assure you this is a positive solution but i would recommend running your car as you would normally get on the highway and then while the light stays on going to AutoZone (They will run service engine soon checks for free) or a mechanic you trust. hope this helps.

Usually the loose gas cap problem code will clear itself after starting the engine a few times once the problem is solved. If you want to use an OBDII code scanner, most of the newer model scanners will allow you to clear codes as well.

One of the hardest codes to track down.

The system has detected a misfire that cannot be attributed to any one cylinder.

The best way to go is cheapest first, so install new, properly gapped spark plugs and replace the plug wires. That will leave only the much more expensive coils and ignition control module for that system.

If no change then move on to the fuel system before spending big bucks.

also this could be caused by bad fuel performance or clogged injectors so change the fuel filter, check fuel pump performance, and first try a fuel injector cleaner before removing and cleaning them or replacing them.

O2 sensors are relatively cheap and could possibly set off the code.

If all this fails ( basicly what you have done is a tune up) I suggest having the car put on an engine diagnostic computer to possibly track down the source of the misfire.

Changing out any of the more expensive parts without knowing if it will repair the problem is not a good idea and is costly, an engine diagnostic will cost around $100 and is well worth the money when the tune up has not improved the situation.

All you have to do is disconnect the negative battery cable for 5 minutes and this will reset you computer to factory settings.... That will not clear it and even if you do get it to go off you still haven't fixed the problem and it will come back on.

P0422 talks about catalyst efficiency. P0300 is random multiple misfires.

http://www.troublecodes.net/OBD2/Pcodes.shtml

there is a code set by the cars computer. you need to have the car scanned to see what the code is. alot of the times getting gas while the car is running can set a check engine lite. There is a difference between the service indicator light (yellow) and the check engine light (red). Also, to those people who say check the manual, we did. The manual gives the smallest description in the book for this light. It says to see the dealer service department. It doesn't give any examples as to what the problem could be.

Trouble code P0645 means: A/C clutch relay control circuit

Well i don't know but if you look in a car book you will find out

Trouble code P0340 means:Camshaft position sensor circuit malfunction