P0172 and P0175 both codes are system too rich (Bank 1 and Bank 2). I reset codes and they came back shortly after. Does this mean I need a new MAF sensor? What else could the issue be if not the MAF? Thanks

Vacuum leaks are common issues. that would be a lean condition though

If the engine is REALLY rich?? the oil separator can cause that. or like you suggested, the mass air flow sensor

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MERCEDES Benz Master Guild Technician (6 TIMES)
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Classic codes for failing MAF. You could try cleaning it with CRC MAF cleaner (Pepboys, O'Reillys, etc). Generally you need to remove the insert (sensor) from the housing to spray in the right places. DIYs online.

The risk of running with a bad MAF is overheating the catalytic convertors and their demise; and of course poor fuel economy.

Be sure to get the correct OEM BOSCH MAF.

Good luck.

All these engines need MAF replacement.

__________________
Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

This vehicle is equipped with the M272 engine. It uses an entirely different engine management system than it's predecessor, the M112. MAF sensor failures are extremely rare on these engines. The most common cause for MAF fault codes, in my experience, is an incorrectly installed air filter housing or, a torn/deformed seal where the MAF sensor fits into the housing.

I've also had a handful of cases where engine oil contaminated the engine wiring harness, causing a super-rich running condition. These were all on higher mileage vehicles. Good luck.

This issue is still present in my mothers car...........Could spark plugs be causing this? I have checked all vac. hoses can't find any that even start to look suspect. I replaced the MAF. I have checked the gasket that seals the MAF. I have made sure that the air filter housing sits totally down on the MAF. I have read a few things on other sites.

Possibilties:
Spark Plugs
Front O2 sensors
Faulter temp sensor (engine is thinking it is still cold giving it more fuel)

Anyone have any thoughts on any of these suggestions?

MB Doc. How could I check the oil seperator, or do you just take a gamble and replace and hope it fixes the issue?

Before replacing the oil separator, make sure that the vacuum control flap diaphragms &
linkage on the back of the intake are not broken OR leaking.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator