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. 

0 Ð Bounty Awarded
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 they always had a broken tps wire. and I'd have 5v, ground and nothing on the third wire. I'm not saying the DME is good or bad just that 5v on the signal wire is not to dwell on.

0 Ð Bounty Awarded
Nicholas Diagnostician
Brooklyn, New York
Nicholas
 

Hi, I would try reflashing DME and resetting adaptations.

0 Ð Bounty Awarded