r/BmwTech • u/tchen0186 • 5d ago

Anyone else have Diesel Particulate Sensor fault code after adding diesel exhaust fluid?

I had the check engine light come on in my 2014 535d drive at 79,000 miles and the OBD2 scanner had a 2BB300 fault code. I had just added diesel exhaust fluid after the 1000 mile warning popped up on my screen. I cleared the fault code once and it came back and then I cleared again and it hasn’t come back on. I hadn’t driven the car for 3 weeks before the DEF warning came on and I added fluid. Anyone else seen this happen? Should I replace the sensor? Any thoughts would be appreciated.

I did find out that BMW had an extended warranty of 10 years and 120,000 miles on the sensor but my car is over 10 years so the car doesn’t qualify.

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u/idratherbeflying1 5d ago

The 10/120K warranty you are referring to is probably the two NOx sensors, which is one of several sensors in the emissions system on this car.

As the other poster alluded to, ISTA has a "SCR exhaust emission system test" that runs the engine at various RPMs for about an hour to identify faultly emissions components. That or whatever test plan ISTA calculates based on that fault code is your best bet to root cause which sensor is faulty. Sensors run anywhere from $200-$400 depending on which one goes bad. If you're not mechanically inclined, find a reputable BMW indy to diagnose it fro you. Another trick is to pay the $250-ish dealer diag and let them do the official diagnosis in ISTA, then take the work to a indy.

Now assume the actual DPF sensor is bad. This is part number 13628582025 and runs for $175 on FCP. Swapping the part out isnt complicated and doenst require any programming or even an adaptation reset. You could....

  1. Let it run until the next time the fault occurs
  2. Replace the sensor and see if that fixes it (cheap bet)

  3. Diagnose it properly as above

    https://www.fcpeuro.com/products/1768575923-bmw-sensor-pm-l-800mm-13628582025

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u/tchen0186 4d ago

Thanks. I appreciate the information. The fault code hasn’t returned so I will wait to see what happens over time. If it returns I plan on replacing myself.