[Fixed] Volkswagen Transporter 2014

Hi everyone. Please accept my apologies for the long narration.

Kindly assist with the following:

Make: VW
Model: Transporter
Year: 2014
Engine code: CAA (biturbo) diesel

I retrieved DTCs from the vehicle using VCDS and the following three codes appeared:
1 11900 - Control Module Malfunction - Internal Altitude/Pressure Sensor (P1387)
2 11901 - Manifold Pressure / Boost Sensor (G31) P0236 00 [167] - Implausible Signal
3 11902 - Manifold / Barometric Pressure Sensor (G71) / (F96) P0106 00 [039] - Implausible Signal

I performed the following tests on the wiring:
1 Manifold Pressure / Boost Sensor (G31)
Ground (black wire) – lights 350mv test light
Ref voltage (grey/red wire) – reads 5v plugged in and unplugged
Signal (grey/white wire) – reads 5.6v unplugged and 3v plugged in
2 Manifold / Barometric Pressure Sensor (G71)
Ground (brown/green wire) – lights 350mv test light
Ref voltage (yellow wire) – reads 5v plugged in and unplugged
Signal (blue wire) – reads 5.6v unplugged and 1.3v plugged in
3 I have further performed the following tests on the Barometric Pressure Sensor and Boost Sensor:
Using a test light, short the signal wire on the Barometric Pressure Sensor to ground, a change to zero volts, can be observed on the scan tool and a DTC of sensor signal too low is observed. Using a test light, short the signal wire on the Barometric Pressure Sensor to battery positive, a change can be observed on the scan tool and a DTC of sensor signal too high is observed

Using a test light, short the signal wire on the Boost Sensor to ground, a change to zero volts, can be observed on the scan tool and a DTC of sensor signal too low is observed. Using a test light, short the signal wire on the Boost Sensor to battery positive, a change can be observed on the scan tool and a DTC of sensor signal too high is observed.

When I short both signal wires to ground respectively, the DTC - Control Module Malfunction - Internal Altitude/Pressure Sensor (P1387), goes away.

4 The above tests confirm the wiring integrity of both the Barometric Pressure Sensor and Boost Sensor. However, here is freeze frame data:

Engine speed: 0.00 /min
Normed load value: 0.0 %
Vehicle speed: 0 km/h
Coolant temperature: 67 °C
Intake air temperature: 34 °C
Ambient air pressure: 820 mbar
Voltage terminal 30: 11.740 V
Unlearning counter according OBD: 40
Charge air pressure: actual value: 2120.2 hPa
Intake air pressure sensor after air cleaner: raw value: 333 hPa
Engine status: COENG_READY
Outside air temperature: 28.5 °C
Particle filter: difference pressure: 0 hPa
It is clear from freeze frame, that the tests are performed KOEO, and the following puzzled me:
Charge air pressure: actual value: 2120.2 hPa (2.1 bars/ 30 psi), this is above atmospheric pressure,
Intake air pressure sensor after air cleaner : raw value: 333 hPa (0.333 bars / 4.8 psi), this is a vacuum,
Ambient air pressure: 820 mbar (0.82 bars / 12 psi), I believe this value to be correct, as all the vehicles I attend depict ambient pressure at 820 – 860 mbar, I am situated in Soweto, RSA.
The above values of Ambient air pressure, Intake air pressure sensor after air cleaner (aka Manifold / Barometric Pressure Sensor (G71))
and Charge air pressure do not change KOER.

At this point I did a bit of swaptronics and luckily, another friend was working on the same model but with a slightly different engine (single turbo). With my kind of luck, same (exactly) DTC.

Please help with finding a solution to this, many thanks.

Regards

With all pressure faults it might be worth doing a smoke test on the intake system. Also check that there isn't a blockage [air filter possibly]

Right at the beginning what stands out to me is 350mv on manifold pressured sensor ground. Try back probing the ground pin and jumpering it straight to a ground on the cylinder block

Thank you for the replies, guys.

I am sorry for not updating the post sooner.

After dedicating 3 days to the vehicle, I discovered that another mechanic has previously worked on the vehicle. He attempted to solve a P0299 without success.

I discovered that he had installed the boost pressure sensor where he was supposed to install the manifold pressure sensor and had installed the manifold pressure sensor where he was supposed to install the boost pressure.

I switched the sensors around and was able to solve the three codes that I had. However the P0299 returned and after extensive testing, I realised that the boost pressure sensor was faulty and installed a new one. The vehicle is 100%, thank you once again.

How did you find out they were switched?

At some point another friend driving a VW Amarok, came to visit. Although the engines were not identical, the engines are the same and I wanted to do a swaptronics on both these sensors. When I was about to remove the sensor from the Amarok, it immediately struck me as I saw it immediately. I wish I could tell you that the fix was based on skill, but it was not.