Looking for help with a 2009 C300 with 63k miles. Engine light came on and it began to lose power. Took it in to a reputable shop and initial codes were:

• P2004 or (0521 Diagnosis of tumble flap ’intake manifold’ : short circuit to ground of sensor lines / tumble flap shaft stick in the actuated position)
• P0607 or (0439 The electronic analysis system for the O2 sensor in the engine control unit is defective)
• P2337 or (0565 G3/4 [right O2 sensor, before TWC {kat} ]: voltage is too high)
• P2240 or (0569 G3/3 (left O2 sensor, before TWC{kat}] : voltage is too high.)
• 0644, 0629,0649, 0636 (combustion misfiring)
• 2193, 0443, 0447 (O2 sensor cylinder bank 1 and 2 faults)
• 0450 (ICU fault in processor)
• 0565 (O2 cylinder bank 1 electrical fault)

On the Garage's recommendation, I had them replace spark plugs, all 4 O2 sensors, intake manifold and ignition coils for cylinders 1, 2, and 3. It was due for serpentine belt (so I was told) and had that replaced.

Worked great for 3 weeks and 75 miles and then the check engine light came on again. Had a buddy scan it for me and it produced the following codes:

• P0174 0341 (self adaptation of mixture formation for enrichment at partial load for the left cylinder bank above the permissible limit.)
• 2093 (the mixture in the left cylinder bank is too lean in the partial load range)
• P2A03 0777 (The single of the oxygen sensor upstream of the catalytic converter of the left cylinder bank is shifted towards ‘lean’)
• P0159 0515 (G3/5 Left O2 sensor after TWC aging)
• 0600 (O2 sensors upstream TWC: plug connections of the O2 sensors are wrongly connected)

Took it back to the initial service shop and they ran their own scan but I don’t know the codes. They also ran a smoke test. They are recommending change the mass air flowmeter, engine air filters, left air intake and air intake gasket for another $1000.

They indicated that if that doesn’t work then I would need to take it to a dealership for a new electronic control module.

So my gut feel is that the MAF has nothing to do with this problem, as the MAF has failure codes of its own, though I do understand that the MAF would have impacts on the downstream sensors. I am more inclined to suspect the issue is with some leak in the intake specifically on the left bank, but there was (supposedly) a smoke test done, and that didn't reveal a leak.

Does this sound like an issue that a good air mass flowmeter cleaning (if even implicated) with new air filters and maybe a new left air intake can solve if I do it myself?

Prior to this latest episode I had planned to drive this car with my daughter to Clemson (past LSU and Alabama) and leave her with the car in SC. Plan B is to give her my Texas Cadillac (F150) while I sort the Mercedes issues.

thanks for any advice!

 

So, minus all the detail above, I wonder if anyone has heard of a MAF that is marginal enough to cause downstream problems on only one bank of cylinders, that does not trigger a CEL for the MAF...