Codes P10D9 and POOBD

Tiny
VALARIBA
  • MEMBER
  • 2011 BMW 535I
  • 3.0L
  • 6 CYL
  • TURBO
  • 4WD
  • AUTOMATIC
  • 110,000 MILES
A few days back I got an engine warning. Every code was in regards to low fuel rail pressure. Everything pointed to a clogged fuel filter. I replaced the fuel pump and filter located inside the fuel tank. Yet the engine still had problems. I replaced both the high and low fuel pressure sensors. Still issues. Also now I have a airflow to high in addition to the low fuel rail pressure. Here are the current codes:
P10D9
POOBD
Thursday, June 25th, 2020 AT 2:00 PM

4 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
I attached the info on this code. If you replaced the pressure sensor then the other possible causes are wiring or the Digital Motor Electronic control module.

Take a look at this info. You need to monitor voltage from the sensor to the DME at the DME and see what it is on each wire. I attached the wiring diagram. Let me know what you find on each wire and that will tell us if the wiring is okay. If it is then the DME is the issue.
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Thursday, June 25th, 2020 AT 7:49 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

The P10D9 indicates there is less than 5 mv variation sent from the fuel rail pressure sensor. Basically, it appears frozen to the PCM. Did this happen since you replaced it? If it has, I have a feeling the sensor is bad. Other than the sensor, it could be a wiring issue or the DME itself could be bad. Confirm there is no corrosion or damaged pins at the connections.

The other code, P00BD is related to the mass air flow sensor and you are already aware. Have you done anything with it? Once again, this is pointing to a circuit issue rather than a sensor.

I have attached two pics below. One is for the low pressure fuel sensor (pic 1) and the other is the fuel rail pressure sensor. The schematics show the pin orientation at the DME. I would check to make sure there isn't an issue with the connection.

Also, if you haven't, the CAN bus system should be scanned to see if there is a break down in communication between the modules. Here is a video showing how it's done and why:

https://youtu.be/InIlnsjOVFA

Let me know what you find.

Joe

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Thursday, June 25th, 2020 AT 8:12 PM
Tiny
VALARIBA
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Okay. So MAF warning was due to an improperly reconnected hose after reassembly on my part. That is solved. Back to the rail issue. I have replaced both sensors but did not replace the rail (located behind the throttle body) 2011 suggest that the rail and sensor be changed together however I feel this would have thrown different codes if that was the case. There was no corrosion that I noticed. Also code reader indicated fuel pressure sensor "stuck".
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Tuesday, June 30th, 2020 AT 1:25 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
The idea that it indicates it's stuck, I have a feeling the sensor you have is bad. Was this code present prior to replacement of the sensor? The DME is recording little to no variation in the sensor voltage output, so it thinks it's stuck or not working. If there is no evidence of wiring issues, corrosion, or anything that appears out of place, I have a feeling the sensor is no good.
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Tuesday, June 30th, 2020 AT 9:56 PM

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