godspeed09BT

2009 E320 BT
​90k service performed.
new fuel filter, oil change, air intake to incled MAF sensors,
New air filters.
Runs fine. Now engine codes P2633 and P0101
Possible causes and solutions?

BenzKraft

P0101 is the generic OBDII MAF code which doesn't say too much, it could be an air leak or excessive air/lean condition. I believe the P2633 is "Charge air system, offset drift under engine load", I've also seen "Fuel Pump B Control Circuit Low" when I scanned using my iCarSoft MBII. I think the former one is correct for this car though. So this would indicate an air leak and most likely in the exhaust side of the charge air system but can also be in the intake side when the engine is under load. If someone replaced the air filters maybe they didn't attach the piping to the filter housings properly. I would check that and if possible test all the intake hoses for leaks. Visibly inspect the piping going from the front grill to the air filter housings and to the MAF ("batwing") assembly to make sure they are inline as it's easy for those to not be installed correctly after replacing the air filters. If you can do an air pressure test from the turbo inlet you might find a slow leak somewhere. The turbo hose(s) going to/from the intercooler can/do rip and leak slowly and gradually until you get a boost leak code. Eliminating those possibilities, there could be a slow leak in the exhaust side (EGR piping).

Try that and let us know what happens!