I drive and spend a lot of time working on a E53 X5 (M62 engine). My neighbor has a 2009 528xi (N52N) that is giving him trouble and I am trying to help. For a couple of days he has been getting intermittent "Engine malfunction! Reduced Power" warning and reduced power. It comes and goes. The CEL does come on, but has always been off when he gets it to me to scan. I have the BMW specific AutoEnginuity software so I can check every module. When I scan the codes, there are three related to the accelerator pedal, but the car still seems to respond correctly to the accelerator - the codes are 2D1B "Accelerator Pedal Module, Pedal Sensor Signal 1", 2D1C "Accelerator Pedal Module, Pedal Sensor Signal 1" and 2D1F ""Accelerator Pedal Module, Pedal Sensor Potentiometer".
Valve cover gasket was done about 3 weeks ago and it had been fine since. Spark plugs and all the coils were all replaced about 6 months ago.
I was a little worried about the fuel pump, but there are no codes for it and the fuel pump reports its voltage as 10.7V at idle and 8.2A current. Both values go up as you increase throttle. The reported fuel pump RPM is 6250 at idle and increases with throttle.
Any ideas? Hate to blindly throw parts at it...
It sounds like your accelerator pedal is faulty.
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Seriously. Follow the codes. Why are you looking into the fuel pump when you have codes for the accelerator pedal?
ASE and BMW Master Certified Technician
Thanks. I know, why not check the obvious first? On my E53 the codes always seem to be something related but not the actual defect. But this one was pretty obvious when we dove into it. Decided to disconnect the throttle pedal to inspect it, maybe clean it some, and discovered everything in the area was wet (fresh water, not coolant). So, figured out he's got a water leak and the water seems to be messing with the pedal. Cleaned up the carpet good with a shop vac, and blew out the pedal assembly with compressed air, and the errors have cleared. Now he has to figure out where the water was coming from...
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