Recently my 2010 BMW 320D had been playing up. Overall performance of the car has been fine. But this weekend it started to struggle to accelerate on the highway for few seconds and was fine afterwards. Yesterday it threw orange engine light. With the odbii diagnostic tool identified P115C as the error code.

Will that be MAF ? enter image description hereenter image description here

Idle stats

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  • That does seem low, but without something to compare it to it's hard to say. What does the MAF read at idle and how are fuel trims? Can you do a rolling WOT run from 2nd gear to 3rd and record a log?
    – Ben
    Aug 16, 2017 at 22:29
  • Updated with idle stats
    – user154856
    Aug 17, 2017 at 1:28

1 Answer 1


According to the interwebs, P115 is "Engine Coolant Temperature Sensor Circuit 1 Malfunction" (https://www.obd-codes.com/p01-codes). I'd start there. Make sure the sensor is reporting realistic values, i.e. ambient temp at cold start, slowly rising to operating temp of 80-110C (not sure what your vehicle normally goes to). If everything looks good, reset the code and see if it comes back.

I have found a few sources on the web that state P115C is a MAF code for BMW. It doesn't necessarily mean the sensor is bad, but it might be worth cleaning the MAF, clearing the code, and see if it comes back.

I've also found a list that doesn't have P115C, but does have P1151-P1159 and they're all related to the O2 sensors. If the code does come back, it may be worth checking your O2 sensors. How many miles on the car?

  • Thanks for your valuable input- My understanding is p115c for bmw e90 2010 m3 translates to MAF sensor ?
    – user154856
    Aug 18, 2017 at 4:05
  • Ah, yes the P1xxx means that's it's manufacturer specific. I was thinking it was P0115.
    – Spivonious
    Aug 18, 2017 at 12:49
  • Turns out there is a hole in the "Hose from radiator bottom — thermostat" :( thats gonna be bugger to replace.
    – user154856
    Aug 20, 2017 at 0:33
  • It's good to fix coolant leaks, but I doubt that was the cause of your issue. I don't see how it would affect the car's performance unless you were out of coolant and the engine was overheating.
    – Spivonious
    Aug 21, 2017 at 12:59
  • 1
    You definitely want that fixed ASAP. Turbos get super hot and need oil and coolant to keep them from being damaged.
    – Spivonious
    Aug 25, 2017 at 14:00

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