I just had codes pulled for a CEL that came on a few days ago in my 99 ML 430 (75k miles). The scanner at Autozone said it was the oxygen sensor on Bank 2, sensor 2. Here are my questions:

1) which side of the car is bank 2, driver's or passenger's? (I just searched old postings here and found ones that go both ways, but I believe bank 2 is driver's, but never hurts to double check) Also, since I am double checking, sensor 2 is post-Cat, right?

2) Is the Bosch sensor that MercedesShop sells as part # C5010-180636 a universal or is it ready to go with the plug on it? I prefer the ones with the permanent plugs, not the universals with the wires w/o connector.

Thanks.

I too have a ML430 (1999) and Auto Zone pulled some codes for me because of a check engine light at 77,000 miles. They claimed O2 sensors but I decided to have them clear the codes and I waited for new CEL to come on.

I don't remember all the details but once I got the codes, I eventually decided the issue was NOT O2 sensor but MAF. That was 50,000 miles ago. I still have original O2 sensors and the replacment MAF is performing perfectly.

I recall the codes being something like P017 something. My hesitation in replacing the o2 sensors is the Auto Zone guy could not tell me which was left or right and whether before or after the cat. There are 4 o2 sensors in total in the ML.

sorry I can't help you out with the universal vs "connector" attached. But I do recall a SUBSTANTIAL premium for the "direct" replacement. Don't forget to check the Bosch USA site. The can show you both options for sensors. Good luck.

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Jim

2 additional thoughts.

I presume your gas cap is on tight and that you haven't overfilled the tank.

Additionally, I trust you have not been using regular octane gas (yes, at $3+ a gallon, we're all tempted to do this) I do recall one instance where the wife filled a few times with reg octane fuel. CEL light came on. Re-filled a few times with high octane and eventually CEL light out. Has not been on again in over 30,000 miles.

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Jim

I replaced the MAF 1.5 years ago. I run premium fuel, and know all about loose gas caps as wife does it all the time on her car. I am pretty sure that this time the code is in fact for an O2.

Anyone out there that can give me a clear answer as to which side is bank 1 and which side is bank 2?

According to prior posts by both Ron in SC and TBGeoff, these gentlemen state Bank 2 is the driver's side.

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Jim

Got the new sensor and was about to change it, but I was wondering: should the CEL go out on its own once the new sensor is in, or do I need to take it somewhere and have the code cleared? I had the code read at autozone, but the truck has been driven a bit before I got the part so the light is on.

CEL light should eventually go out by itself.

Correction: I'm now not so sure about the O2 sensor. I know it will go out if the MAF sensor is bad and you replace it with a new one. I am not so sure if this also applies to an o2 sensor.

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Jim