Hey all. We are about to head for Lake Powell for some water skiing and the damn check engine light has come on our '97 C280 (silver/dark leather w/65K mi). Hoping you can shed some light.

I suspect the light means the mass airflow sensor or one of the (rear?) 02 sensor, but would like to confirm first. The nearest dealer wants $100+ to read the codes AND I have to drop it off. I called a few of my local San Diego County Peb Boy shops. Only a few do it, and those have to make an appointment because the tech that does it is not always in. Oh, and it'll be $85 bucks. Still no way to get a fast diagnosis. I can't wait three days.

FYI: For good measure, I checked the gas cap, the throttle position sensor and then pulled the MAS and sprayed some carb cleaner on the hot wire, then I climbed under the car to inspect the two 02 sensors. Everything is intact. I fired up the car, and took it out for a romp. It runs great! In fact, it hauls ass for a 2.8! The light is still on, but it idles and shifts fine and I can't find a damn thing wrong with it.

So what's this about an "onboard diagnostics" -- is there some kind of DIY utility on the car that I don't know about? I know tons about Porsche, but not near enough about MBZ. Guess that's about to change.

Deductive reasoning: all the parts guys I spoke to today say the MAS is a regular sales item. It's a 3-minute replacement part. That's the upside. The downside is that the friggin' thing costs $250±! The same parts people I polled do not stock the front 02 sensor -- only the rear, so that tells me the fronts do not go out often. The upside is that the normally stocked 02 sensor costs $125±. The downside is that it looks like a total pain in the @$$ to remove! It's in the middle of the "Y" at the back of the catalytic converter. How the heck are you supposed to get a wrench on THAT!?

Ready for a family vacation, so any ideas would be very much appreciated!

You lower the rear of the exhaust & support it & use a special O2 sensor socket to remove the sensor.

With ODB2 on that car almost any scanner will bring up codes that should lead to a correct diagnosis.

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Thanks Doc. Now why didn't I think of that!?

Anyone know if a 1997 C280's CE light will go out by itself, once the problem has been fixed? Or does it need to be reset?

Hey, Bob. Why don't you rent a vehicle and take off on vacation? The fix can await your return. Have a good time.

Yeah, that's probably where I am heading, I guess. I just hate to throw in the towel if it's just a quick 02 and MAS replacement.

Better than it coming on in the middle of Podunk Arizona though!

Bob,

Check out www.europarts-sd.com, they sell parts for MB at a discount and are located in Rancho Bernardo. Also Partsshop can get a part out overnite if necessary so you can have it by the next morning.

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Thanks! Actually, I was going to use them or Inter Auto Parts (Convoy Street in San Diego) today after I get my codes read at the local 76 station.

Make sure you look before you leap. You can speculate on what DTC has been set, but you just can't know until you draw the code.

If you have a laptop computer, or are willing to drag a desktop to the garage, you can buy EASE Diagnostics or other software systems for a few hundred dollars. At $85 a pop, you won't have to draw very many DTC's to get your money back.

I wish I could line up as many cars down the road as I could to keep the que full awaiting my drawing a trouble code for them at $85 a pop. I would be retired in the Bahamas in about six months.

Have a great day,

Larry,
I heard of the ODBII for reading code, What is needed and how and where do you connect the laptop on the car, also where I can get the software..thanks 98 w210

Not only is shot-gun changing of parts walking around with a blindfold on and your wallet hanging out in a subway, but even after you have the codes , it still doesn't mean you have identified a faulty part .. it means the computer has detected a fault in a SYSTEM... broken wire , leaking hose , unplugged sensor, etc, etc ,.etc...

Get the codes .. period.. then check out the sytem the code is DIRECTING you to..
If you saw how many codes can trigger a CE lamp, you would not bet on anybodys past CE lamp rectifying part change, believe you me....
You can get code lab-top interfaces that do the job for as little as $75...
and after you get the codes , post back here and you will then get some experienced,analytical direction/answers..

Okay, got the error code checked at my local Union 76 station. They guy was going to give me a freebie, so I flipped him $25.

So here's the scoop on the CE light error code: 00171 or P0171, meaning "system too lean, bank 1" according to this MBZ OBD2 fault code manual

Now if I go to a different MBZ OBD2 error code link, it also adds "faulty mass air sensor" to the description.

Can anyone confirm this is the correct interpretation before I go out and spend $250 on a new MAS?

Thanks!