Check Engine Light Not Resetting Despite New MAF Sensor

New NGK spark plugs, Beru wires, Mann air filters... etc.
As part of this tune up, I decided to go ahead and get a new Mass Air Flow sensor. (MAF)
I purchased a Beck Arnley unit, part number 18452-05218068 from PartsGeek.com.
When I installed the new MAF, I accidentally forgot to plug the new sensor in. As a result, the C55 ran rough upon the first start since the installation of the new MAF. I quickly realized what I had done, stopped the car, plugged the sensor into the harness and restarted the car. It ran smoothly and I assumed the MAF swap went as it should.
The next day, the check engine light illuminated on my way to work.
I assume the light came on since I started the car with the MAF unplugged, but now that the new MAF is plugged in, I read from a post that the check engine light should go away by itself.
Has anyone on this forum had a problem with a Beck Arnley MAF when equipped to an AMG'ed M113 (C55 engine)?
I have not done anything else to the car yet, since I want to resolve this issue first before changing the spark plugs and wires.
On a side note, I did order an OBDII scanner, finally!





Case in point:
PartsGeek lists the following MAF choices when searching for a 2005 C55:
Choice 1:
Bosch Air Mass Meter
Retail Price: $414.00
Your Price: $182.85
Part Number: W0133-1601501
Condition: New
OEM
Choice 2:
A1 Cardone Air Mass Sensor
Your Price: $158.85
Core Price [?]: $28.80P
Part Number: 18452-05004975
Notes: Mass Air Flow Sensor -- Remanufactured
Condition: Remanufactured
Choice 3:
Beck Arnley Air Mass Sensor
Your Price: $163.85
Part Number: 18452-05218068
Notes: Mass Air Flow Sensor -- New
Condition: New
Choice 4:
Bosch Air Mass Sensor
Your Price: $134.85
Part Number: 18452-05219116
Notes: Air Mass Sensor - New
Condition: New
So as you can see, there are 4 choices, two of which are manufactured by Bosch.
One thing that totally slipped my mind was that only Choice 1, has the OEM designation. This leads me to believe that the Beck Arnley unit I purchased is not the exact MAF that I should be using. The sensor used in the Beck Arnley unit may have a differently scaled signal or have something largely different than my stock MAF unit. I am going to wait until my OBDII reader arrives before I consider an RMA. My commute is about 25 miles each way, so if the check engine light is still on by Wednesday, I will be pretty sure the ECU does not like something about the Beck Arnley MAF.

If your engine is still smooth as butter, then I guess there really is no reason to change it...

CEL is still not gone, but something I did notice is that the transmission up shifts a hell of a lot faster and my gas mileage is horrid.
I will still wait until Wednesday and get the actual codes out of the car with the OBDII reader, but I am leaning toward this Beck Arnley MAF sensor being the incorrect part.
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OBDII scanner arrived on Wednesday.
I interfaced with the car and was able to pull two codes. I do not remember the exact codes at this exact time, but they both said "Bank 1, mixture too rich" and "Bank 2, mixture too rich". (Or something very close to these descriptions.)
Obviously, these are MAF (Mass Air Flow) sensor related. (Or rather related to when I started the car with the new MAF unplugged.)
I decided to clear the codes using my nifty new OBO II tool. The check engine light turned off, and I went for a good 30 minute test drive around town. The car appeared to be behaving very well, my gas mileage was back up to normal levels, no ultra quick up shifts anymore either.
The car went into the garage with me thinking that the problem was gone...
Nope... that would be too easy!

Check engine light returns on my way back from lunch today. At the end of my lunch break I checked to see what the codes were, and the same two codes had returned.
When I got home I double checked my installation of the MAF to ensure there were no leaks or folded seals around the MAF ducting areas. No issues found, I double checked the connector going to the MAF to ensure it was seated all the way and it was perfectly fine.
I am going to RMA the new Beck Arnley unit, reinstall the old OE Bosch unit, make sure everything is back to normal, then get a proper Bosch replacement.
So boys and girls, I just got shot in the face by the
"If It Ain't Broke... DONT FIX IT" troll.
Just my luck.


Rear of engine, MAF removed along with elbow housing.

New Beck Arnley next to old Bosch MAF unit.

Picture of the elbow connector. MAF connects to top port, bottom port connects to throttle body.

Since I had everything apart already, decided to clean the throttle body. Everything had a light coat of oil/dust/dirt.

Using a shop rag, got it to this point.

Another shot of the elbow connector, notice the greenish tint, I think Mercedes-Benz used some kind of sealant around the rubber seals... anyone have any ideas what to replace it with, if anything?


Bring in the Q-Tips!

The best I could get it.

Transferring the MAF mount ring back to the old Bosch unit.

Below the Chrysler text is the PVC vent hose that makes the throttle body get oily over time. Be sure to reconnect it!

MAF back in.

Another picture of the collar mount ring that goes around the MAF unit.

Does everyone's right intake hose have this crease?

Old MAF is back in, check engine light reset, been driving 50 miles a day for the last 5 days, no CEL light so far. Returning the Beck Arnley unit, getting a new Bosch unit.
Last edited by Rahulio1975280C; Jun 24, 2012 at 09:17 PM.








