zoink

I have W210 E55 and got P0170 and P0173 codes. Replaced the gas cap and the codes went away for couple weeks. CEL is on again now

Next educated guess is MAF and/or O2 sensor. Prefer to fix MAF first as I don't think replacing O2 sensor is a DYI job.

So... after reading the threads here and couldn't find any definite answer, here are my questions:

1. Would it be better clean the MAF or just replace it?
2. If clean the MAF, what should I use? Use compressed air, an electronic cleaner or dip it in 90% rubbing alcohol?
3. Is replacing O2 sensor a DYI job? I think the answer is no... but who knows If the answer is yes, could anyone give me some instruction?

Thanks!

sosh

Cleaning a MAF is not reccommended. They are a consumable and should be replaced.

StapleGun

Just so you know, I had the same EXACT codes...Fuel Trim, Left and Right banks, respectively. I attempted cleaning the MAF to no avail...and ultimately had to replace the MAF. I found one on ebay for about $200 including shipping. It is a very, very easy DIY. I think your engine is a 113 too, but check...this is applicable to my vehicle, a 1998 C43.

(1) Remove your air filter housing
(2) Remove the electrical plug on the side, it has a tang that must be depressed to remove.
(3) There's an additional tab on the lowermost portion that must be depressed for its removal...which if I remember correctly you may need a screwdriver to access.
(4) Once the MAF is off, inspect the rubber manifold which is underneath the MAF, for cracks and or potential trouble spots. Now is the time to replace it, if need be. These can harden over time and crack in the joints. I cleaned the rubber manifold with alcohol and added a tad of petroleum jelly - very little.

PLEASE NOTE: There is nothing that should be forced for its removal, if you are, then you're doing it wrong. Remember to cover the intake underneath the MAF - you certainly don't need ANYTHING falling into it. It's a half hour to an hour job, and it takes that because I tidy up everything while I'm there.

zoink

StapleGun, thanks for the info.... I did indeed try to inspect the MAF last night and yes, it was easy to uninstall and re-install it. The MAF appeared quite clean... I wiped the inner portion (not the sensor) w/ a towel and didn't find any dirt at all Could be the MAF just dying, or is it an indicator that the O2 sensor is the one that fails. Hope not...

So now I need to start looking for a MAF. I know there is a seller at eBay selling an aftermarket one - OES brand or something like that, not Bosch. Anyone knows about the quality?

One last question.... once the MAF is replaced, should I wait until the CEL is off by itself or should I reset it?

PS: I just realized that I typed DYI instead of DIY.

zoink

Just want to share the step-by-step guide to replace the MAF for W210 E55.... I tried to find it here and didn't find one (luckily w/ a picture from eBay I could identify the MAF easily ).... so my apology if it's a repost.

Part Number:
Bosch Part # 0280217810
MB Part # 113 0940048

It should look like the pic below.

Step 1:
Remove the front part of engine cover (the one w/ AMG logo). The cover is held by a bunch of clips. To remove, simply pull up the cover from the front.

Step 2:
Remove the back part of engine cover (the air box). This is held by 2 clips at the front (there is a clip on each side near the air hose) and an air hole at the back (where the air box meets the MAF). To remove, simply pull up the air box from the front. Or you could use a flat screwdriver to pry open the clips.

Once removed, you could take apart the air hoses or leave them connected.

Step 3:
Identify the MAF. The MAF is at the center back of the engine (right below the back air hole of the air box). You can compare this w/ the pic I attach below.

Step 4:
Unhook the electric cable connected to the MAF (on the side).

Step 5:
Remove the MAF. The MAF is held by two-clip ring and a small metal clip at the back. I'd suggest to loosen up the MAF from the metal clip first by prying it w/ a flat screwdriver. And then remove the clip ring. The MAF should be easily pulled up.

Please be sure that there is a rubber ring (like StapleGun said) underneath. Make sure you don't lose it. Would suggest clean it first before reinstalling the MAF.

To install... do the reverse.

Hope it helps!

StapleGun

Hey Zoink, when I had this problem...I was all too glad to take ALL the help I could muster!

zoink

StapleGun: After you replace the MAF, did you let the CEL turn off by itself or did you reset it?

Either way doesn't seem to matter.... but I'd certainly prefer to let it turn off by itself as this would mean the problem has been fixed.

StapleGun

Nope, once the MAF was replaced no more CEL.

kev

here's a how-to on cleaning the MAF:
https://mbworld.org/forums/c36-amg-c43-amg-w202/108994-maf-problems-cleaning.html

although, if you read the whole thing it sounds like it's a temporary fix at best, and may actually make things worse..

zoink

Thanks. Ironically, the guy who started that thread indeed replied to this thread.... It's StapleGun....

He indicated that he tried to clean it but didn't really work.... so replace is the answer.

mleskovar

MAF cleaning works and is well documented on the internet. The recommended method seems to be aerosol brake/carburetor cleaner and lots of care. I don't understand how they become contaminated if you use a proper air filter. Any theories? Spending too much time at redline?

zoink

I don't think contamination is the typical culprit.... could very well be just the electronics itself died. Just like my headrest that was suddenly dead.

As I posted above, I did try wipe the inner part of the cylinder and it's 100% clean (my towel did not pick up any dirt or dust!!!) so I think contamination may not be my issue or ... my MAF may not have any issue at all... who knows. My car idles fine & runs strong like usual (no MAF symptom) ....

But for $200, I'll take my chance replacing it.... if the CEL doesn't go away, I'll take it to my mechanics to take a look at O2 sensor.

mleskovar

No "electronics" in the MAF that get replaced involved. There are only a wire that provides heat and and another wire that changes electrical conductivity as air flow cools it. The condition that causes erratic behaviour is contamination of these wires causing improper heating/cooling of the conuductor and that can usually be removed. Open heater or conductor wire failures are obvious/solid. There's a cycle the heating element goes through after motor shut down that super heats the conductor to clean it but if the contamination is heavy or of a material not affected by heat then it doesn't get cleaned. Not claiming to be an expert, just a good reader.

StapleGun

I meticulously cleaned the MAF, as that link shows...however, the CEL came back on within a day. That is the BEST clean-up of a MAF I have found on the net BTW. It has been subject of much speculation on this forum, if the failure of this item is due to over-oiling K&N type filters. Hence, I now use OEM filters...the headache is not worth it to me. Once I purchased a new MAF, no more CEL. As I stated previously, once I replaced the MAF, the engine was transformed.

Also, refer to that post because I linked a source for the security bits tools from Griot's Auto accessories. The plug located on the MAF has a stud in the middle that prevents the use of a conventional torx screwdriver to be used.