2008 E92 320d - engine fault, reduced power

[medellin]

Hello there lads. I have been having this issue of an error "engine fault! reduced power" in my '08 E92 320d for the past year. I tried to listen to some other advice and already changed my EGR valve and the fuel filter. No progress, the error still appears. More often than not, but not all the time. What's interesting, it didn't show during the winter season. Just as the temperatures started rising it started to appear once again. I'm slowly running out of options and don't want to replace every single part of my car before finally finding a solution. I have been to two mechanics, did as they suggested and it seems to be for nothing. Hopefully someone here can help me out. Greatly appreciated!

[MarcoZandrini]

Have you scanned the engine computer (DDE) for codes? That’s always the first step.

[medellin]

Yes, they did that at the mechanic's. Should've mentioned that, sorry. These are the codes.

003EED DDE: Power management, closed-circuit current violation
004933 DDE: Air system, air to EGR mass flow, plausibility
00494A Preheating control unit?
0049A5 LIN bus : Communication fault
0049A6 as above
004A4E Glow plug, cylinder 3, activation
004A5E same but cylinder 2
004A6E -||- 1
004A74 LIN, message; preheating control unit: Missing
004A79 -||-
00A6DE JBE: Mirror/washer nozzle heating ?

[328 Power 04]

The 4933 error always confuses people and they replace the EGR. It's not an EGR code. That code is for overall air mass plausibility, measured air mass being often lower than expected. Freeze frame data and frequency for that code would be so important. Live data logging should also show where it happens.
Is this car tuned?

[medellin]

Thanks for the input. The car is not tuned. I'm not much of a mechanic and can barely understand what you're saying. Anything I can check/do before going to the mechanic's again (probably a different one)? Also, they said something about a melted(?) glow plug (computer not reading it) and I'm reading that it can cause this error to happen. What should be my next step here? Thanks again.

[medellin]

In case anyone stumbles upon this thread in the future - it was the faulty DPF.