2008 BMW 535xi 2D2A/P1124

Adam Diagnostician Palatine, Illinois Posted   Latest   Edited  
Question
Driveability
2008 BMW 535xi 3.0L (N54B30A) 6-spd (GA6HP19Z)
No Symptoms
P1124a - Differental Pressure Fault

2D2A/P1124: Differential pressure sensor fault.

I have this BMW that has this code that set, according to the customer, set awhile after performing a carbon cleaning. 

Using ISTA: After deleting fault memory the code is sets immediately: no engine start.

ISTA service plan states that it could be the sensor (replaced with new BMW part), connections/wiring (all test good at the sensor and DME) or the DME itself.

Sensor connected;

4.9 at 5v ref

Ground tests good

4.9 at signal

With the sensor disconnected, at the sensor connector:

4.9 (steady) volts at the 5v ref.

Ground has no voltage.

4.9 on the signal

DME and sensor disconnected:

No voltage on either the 5v or signal and wires not shorted together. 

KOEO:

Differential sensor; 0.0 mmbar

MAF: 0.0 K/ph

KOER;

700 rpm

Differential sensor: 44-50 mmbar (increases with rpm/load)

MAF: 3.8 gps 

AIR shows no applicable TSB's or campaigns for the code.

I have tried the adaptive resets to no avail.

Not sure why there is 5v on the Dif sensor signal wire but I have a reading in data: calculated default value?

ISTA service plan says to replace the DME.

Before I do that: Any ideas?

0
Gerald Manager
Birmingham, Alabama
Gerald
 

Check the throttle to make sure the flap is closing completely. Have seen them stick open slightly cause that fault.

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Michael Owner/Technician
Tampa, Florida
Michael
 

I've sen 5 volts on a lot of sensor signal wires even on 2 wire temp sensors. I often use that to tell me the wire is good to the ecu. I would expect to see 5v, 5v and a ground on a thee wire sensor. that is how I confirm good circuits probably not the best way but i find it quick and effective until I get burned. I learn that years ago on an Japanese minivan don't remember the make or model but…

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Nicholas Diagnostician
Brooklyn, New York
Nicholas
 

Hi, I would try reflashing DME and resetting adaptations.

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