Check Engine Light

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

A "Blinking" light typically means that something SEROUS has been detected. Use a code scanner to detect the problem.

If you are referring to the Check Engine light it means there is a problem with the emissions system on the vehicle. Have it looked at by a professional. If you are referring the the Maintenance Required light it means you need to change the oil/filter.

You don't!

Have vehicle scanned to determine the problem. Some auto parts stores will do this for free

Most likely it means your gas cap is loose... or whats called an evap system leak.

The Check Engine Light (CEL) lights up when the Engine Control Module (ECM) detects a problem related to emissions or performance.

It could be a problem that is showing up intermittently. Most of those types of problems are stored in the computer, so you could probably borrow, rent or buy an OBD2 code scanner that would tell you what's going on. Check with your local auto parts retailer. They can often give you a little assistance on those types of issues, especially if you could go in during an off-peak time. Good luck.

The number one reason the "Check Guages" light comes on is for you to check the guages. It is almost always because your temperature guage is reading really high and when you start off,the temp goes down and the light goes out. Another is the oil pressure guage. If it goes low while ideling such as at a stop light, the "Check Guages" light comes on and goes out when you start off again and the oil pressure goes up.

Try removing negative battery cable for 10 minutes. If that does not work you will need an OBD2 scan tool to reset the light.