My ML has had a check engine light on for some months and I don't know what is causing it

I am testing it without the air cleaner to see if that is the cause (dirty air cleaner)

The car is running perfectly, recent oil change; all fluids OK

What else could possibly cause that light ?? Need to eliminate it to pass TX inspection.

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Ben Harrison Carter
1999 Mercedes ML320 87K
1992 Mercedes 300CE 89K
1995 Corvette 29K -- Sold Dec 09
1989 Mercedes 420SEL 99K -- (Sold 4/08)
1968 Mercedes 230S (106K) (Sold 9/06))
1976 Mercedes 450SEL 130K (Just sold - 06)
1961 Mercedes 220Sb (sold years ago)

The CEL usually means one or more emission control modules are faulty. Start by getting an inexpensive OBD scanner online. About $50 for stand alone handheld but only about $25 for one which requires a laptop such as ELMScan 5 (amazon). The codes you get, especially after 6 mos should be suspect but write them down and clear all the codes. Drive for a few days and then rescan. Those are the codes to consider. FYI- Be sure NOT to clear codes just before a smog inspection or you'll get a 'status not ready' error from the smog tester and have to return.

Ignoring a CEL can get expensive. For example, a bad MAF can cause an over rich mixture which in time will kill your CATs.

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Good luck.






1998 E320 Wagon

Ben,

From my chair it can be anything? Get your self a OBDII tester, and run the codes..

A car that old with so few miles says a lot of " stop n go" miles in the city, and the emissions recirculation systems are heavily taxed. In my opinion it always lead to plugged EGR passages/ Charcoal canister / canister valve / air injection / open vacuum line passage. It can be the driver circuit driving these systems from the computer(This was my case on one of my cars).

Really your problem can be anything, but I would not have keep running with a check engine as the one problem that gets worse with time is the plugged EGR passage.. It gets harder to unplug as it gets more plugged. Some cars have a pipe that do this, but the cars that channel the exhaust through the engine block have the risk of some times having to replace the engine, or getting rid of the car because the coat hanger trick on drill to unplug will not work on the one channeling EGR gases back into the intake.

I have 2002 E320 W210 wagon with 170k miles with the same engine as your ML, but highway miles do not cause this as the EGR kicks very little. I have never had check engine on the wagon..

Run your codes...It is the real only suggestion

FYI, the engine gets better running as the EGR gets plugged because the exhaust gases cannot mix into the intake.

All the best,

Martin

I think a dirty air filter is about the only thing that won't cause it. About 200 things that could however. Maybe more.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

I have the basic reader and got a code 110 7 times before taking the car in for O2 sensor replacement. The description of the code said "02 sensor, bank 2 sensor 1" I took the sensor to a Lube and Tune garage and asked them to install the sensor in "bank 2 - sensor 1" position. A note from this site previously said that this sensor would be on the driver's side, pre cat. I believe that is where it was installed, but will double check that today.

I am still getting the same 110 code (3 of them now) and the car is stalling at stops unless I increase the idle slightly !!??

Assuming the sensor was properly installed (??) which I will check -- should it really have been on the driver's side pre-cat ??

Also, what else would cause the Ml320 to stall when stopped in Drive? If I put it in neutral or Park -- which have a higher idle speed, it does not stall.

Please let me have your comments re (1) the proper location of the sensor; and (2) what might be still causing the stalling at a full stop in drive ????

Thanks, Ben Carter

__________________
Ben Harrison Carter
1999 Mercedes ML320 87K
1992 Mercedes 300CE 89K
1995 Corvette 29K -- Sold Dec 09
1989 Mercedes 420SEL 99K -- (Sold 4/08)
1968 Mercedes 230S (106K) (Sold 9/06))
1976 Mercedes 450SEL 130K (Just sold - 06)
1961 Mercedes 220Sb (sold years ago)