P0105 Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction

[Mick B]

Anyone had any problems with this code before. The car is a Signum V6 CDTI 3.0 and I have just replaced the MAP sensor due to this fault and appeared to have sorted the problem. Tonight accelerating whilst cold around 3k revs the management light came on again and good old limp mode. Read the code when I got home and its the same fault again P0105 Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction. If the engine is turned off for 30 seconds the fault clears from the dash. The car also has a pressure boost solenoid with two pipes going to the turbo could this be the problem as it appears to be linked to the same circuit.

Any of you brainy people out there any ideas please.

[omega63]

The barometric air pressure sensor is on top of the ECU, its that round grey thing and must not be tampered with, this measures the current weather air pressure. The boost pressure sensor is fixed to the upper edge of the rear inlet manifold, the air pressure entering the engine at idle is negative a vacunm, ie its being sucked in. The likely cause is the boost pressure sensor reference signal as come within 20 > 30 mbrs to the atmospheric/barometric pressure reading at the ECU. Try cleaning boost pressure sensor CAREFULLY!!!!!!!!!, and see if that cures it....

[jodiexii]

Could be sticking variable vains

[Mick B]

The barometric air pressure sensor is on top of the ECU, its that round grey thing and must not be tampered with, this measures the current weather air pressure. The boost pressure sensor is fixed to the upper edge of the rear inlet manifold, the air pressure entering the engine at idle is negative a vacunm, ie its being sucked in. The likely cause is the boost pressure sensor reference signal as come within 20 > 30 mbrs to the atmospheric/barometric pressure reading at the ECU. Try cleaning boost pressure sensor CAREFULLY!!!!!!!!!, and see if that cures it....

When you say boost pressure sensor we are not talking the MAP sensor Ive just replaced ?

This one

$T2eC16NHJHYE9nzpcw03BRH!Vo6Uhw~~60_12.JPG


Also where is the barometric sensor ?

[Mick B]

Could be sticking variable vains

And how do I resolve that ? Are we talking vain's on the Turbo ?

[omega63]

What i see there is a vacumn actuator switched electronically open/close, the boost pressure sensor is mounted/fixed on the top edge of the rear inlet manifold, you may find pictures in Y/Z 30DT specific of this sensor. The Barometric sensor is mounted in the top edge/face of the ECU, and must not be MESSED!!!! with...

[Mick B]

What i see there is a vacumn actuator switched electronically open/close, the boost pressure sensor is mounted/fixed on the top edge of the rear inlet manifold, you may find pictures in Y/Z 30DT specific of this sensor. The Barometric sensor is mounted in the top edge/face of the ECU, and must not be MESSED!!!! with...

if this is what you mean that's bolted to the rear manifold it's what I have just replaced.

[jodiexii]

Yea variable vains on turbo.
to check these you need to take heat shield off turbo .
then on actuator on turbo take rubber hose off and suck on pipe and see how far actuator arm moves,should be about an inch and a half

[Mick B]

Yea variable vains on turbo.
to check these you need to take heat shield off turbo .
then on actuator on turbo take rubber hose off and suck on pipe and see how far actuator arm moves,should be about an inch and a half

Got ya. I will check that tomorrow so if it moves its fine but if it seized how do I clean them.

So on Crtich's image below is the smaller pipe on the actuator the one you suck near the number 8 ? Also still looking for the
barometric air pressure sensor

[omega63]

Yes thats it!!!, if you have changed this and cleared the codes, then the next step would be to check the induction/intercooler hose for splits and leakeage or at the worst the intercooler itself. You could check the throttle/butterfly valve at the throttle body its operation the actuators and small vacumn pipes etc, what your looking for is something that can cause the boost pressure and barometric pressure to become near equal at one given time ie when the engine begin rev up etc. ....