CHECK ENGINE light came on yesterday.

My 2000 ML320 with 53k miles was delivered to the previous exactly six years ago yesterday. (Previous owner put 26k miles on it in 3.5 years.)

Coincidence?????

Just had plugs replaced.
Truck running great, getting 19-20 MPG.

Strange.....now the light is off.

Truck is getting senile.

Dont worry about it, probably has something to do with adding new plugs and it is getting used to them. Or you could have a MAF sensor on the way out but without codes its almost impossible to know.

put gas in recently? could be a loose gas cap. those seem to cause CELs to come on and off.

How long ago did you replace the plugs?

The CEL coming up could be from either a bad sensor or an actual malfunction of one of the various emissions things on the car. And simply becasue it goes away doesn't mean the problem is resolved - these sensors perform function based on statistical information. So, one day you'll see the CEL and you don't drive for a while and then start the truck and no CEL.

What I advice is to have the trucked checked by a MB shop. They will determine the fault at some minimal cost and it'll be up to you to have it fixed or not - I assume this will be non-warranty work!!. If it's a MAF issue, or even the EGR valve, it's a simple DIY - these both happened to me. If it's neither of those, I'm not sure about the DIY possibility!!!

They're both expensive items and I think you should spend the dough to have the proper diagnostics b4 u replace something and then still have the CEL show up!!!

Darkmann:

The plugs were changed less than two weeks before the CEL came on.


I bought this ML320 in Aug 2004. It had two months left of MB warranty and it had been "StarMarked" (for 12 more months). I bought another 24 months of additional warranty coverage which "covers" me to October 2007.
Of course, not one single problem with the truck in the two years I've owned it.

If it's under warranty, what is thenproblem? Take the truck in and let them figure out what the problem is. But, you have to take it in and make sure the complainbt is recorded before the warranty expires. That way if it happens shortly after and they suddenly happen to diagnose it correctly, they pay for verything.

Be careful and read the fine print on the additional warranty coverage. It may not cover what you think it should cover. I'd like to settle this b4 the original 4/50 warranty xpires.

Keep us posted!!!

So I took my ML to the gas station where I buy most of my fuel.
I asked if they could see what the OBD codes were for my CEL.
Sure..No problem (and no charge).

Code was P0141.
This is an O2 sensor, covered by my extended warranty.

When I went to the dealer they said that for CELs they perform a full vehicle diagnostic check .
Cost $204.75

Since everything was going to be covered, I said to go ahead.
Sure enough, bad O2 sensor, fully covered/no charge.

"Oh, and Mr. Billiken, your tires should be replaced soon and your pad a rotors are all below spec."

Now, less than 24 hours after picking up my "repaired" ML, the CEL is back on.

Of course it's Friday night.
Dealership closed.

And I need to drive 4 kids about 95 miles tomorrow (return next day).

Great.

New CEL is indicating Mass Airflow Sensor.

Replaced
No charge (under warranty).

While mad that I had to drive back to the dealership, I really enjoyed the 2006 ML350 they let have as a maintenance loaner.

Freaky man....
My ML320 also turned 6 this week. I have just shy of 40k miles. CEL came on today. Truck is running tops otherwise.

So these emissions parts are covered under the factory warranty?

The tech told me that the Airflow Sensor was covered by the extended warranty that I had purchased on my ML.

I'm not sure about the O2 sensor (what warranty covered it).

I bought my ML350 in Sep 2004.
It was a 2000 model with 23k miles.
It was StarMarked for 1 year.
I purchased a two-year extension on top of that.
So I've got a 2000 ML with a warranty through Sep 2007.