540d DPF Problems

    Hello!

    2017 G31 540d.

    Previous owner had short trips a lot. Mine have been long and I am not afraid of the throttle pedal so to speak.

    When I bought the car it had 284C00 and 341D00 - Exhaust gas temp codes from DPF and CAT.

    DPF temp would NOT reach above 110C, no matter how I drove. So I ordered BOTH, CAT and DPF temp sensors as genuine BMW parts.
    They were a bit of pain in the ... to replace so that's why I changed both at the same time.

    Issue is that the problem STILL exists after replacing the sensors.. DPF temp WONT go above 110C no matter what. It hovers around 50-110C when driving. No DPF regen is possible because ISTA says that at least 220C is needed for it..

    All other temp sensors seem to be working correctly (SCR, CAT, EGR temps)

    Soot mass - 60g but pressure is ~5 HPA on idle? Is that a bit weird?


    Any help?

    deepl.com

    Gruss


    australia



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    Hi,

    Having the sensors replaced without expected positive effect is a mass, but what about the failures, do you have any entry?

    What about the other temparatures, oil and cooling liquid? Thus the required temps for kicking off the DPF regeneration are not reached, what about the other temps at all? Stays the oil also cool and is not reaching operating temp of approx. 95-105 degrees? If yes, after which distance? Any issues with the exhaust system at all?

    Is the car stock or any tuning software applied?

    530d xdrive Touring, BJ 05/2019, M-Paket, Alpinweiss, ID6

    Update / Solution found


    I finally figured out why my DPF temperature would never go above ~110°C even after replacing both the DPF and CAT EGT sensors with genuine BMW parts.

    The issue was not the sensors at all – it was the wiring.


    At some point in the car’s history, someone who should not work on cars had connected the DPF temperature sensor connector to the EGR temperature sensor, and the EGR temp sensor connector to the DPF sensor. The connectors fit each other and the wiring lengths are long enough, so it looks “correct” even though it isn’t. This was a bit hard to diagnose but after hitting my head against the wall for some time I started to look up everything on ISTA and saw that the sensor wiring is totally different on my car.
    DPF temp. sensor connector is located back of the engine, under the DPF differential pressure sensor. EGR connector about half way of the valve cover, both on exhaust side of the engine.
    Because of this:

    • The DPF temp reading in ISTA was actually the EGR temp
    • The DPF never “reached” regeneration temperature (ECU thought it was stuck at 50–110°C)
    • Regeneration was impossible because ISTA requires at least ~220°C
    • The engine behaved strangely at low RPM because the ECU was trying to compensate for the wrong temperature data

    After swapping the connectors to their correct sensors, everything immediately started working normally. DPF temps now rise as they should and regeneration is possible again.

    So if anyone else has a B57 with low DPF temps and no regen even after replacing sensors, check the wiring – the connectors can be mixed up very easily.