NMS P026A and P0111 Code Diagnosis

[jw4free]

2012 Passat TDI SE

Summary: Engine CEL, Ran Ross VCDS scan, discovered code P026A and P0111. Cleared. Did research. Ordered MAP sensor (G31). Engine CEL again. Ran Ross VCDS scan. Got same Codes. Cleared codes. Pulled sensor. Discovered greenish oil/water condensation froth. Cleaned sensor, and replaced. Engine CEL again. Cleaned upper intercooler area with rag (limited success). Replaced sensor. Success.

Note Sensor G31 and G42 are a combined Bosch MAP and IAT sensor.



Sunday,12,February,2017,14:15:03:12876
(Scan truncated)
12642 - Charge Air Cooler
P026A 00 [237] - Efficiency Below Threshold
MIL ON - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 9
Mileage: 151073 km
Date: 2017.01.30 (Tuesday evening)
Time: 17:06:40

Engine speed: 2142.50 /min
Normed load value: 59.6 %
Vehicle speed: 113 km/h
Coolant temperature: 84 °C
Intake air temperature: 44 °C
Ambient air pressure: 980 mbar
Air mass at air mass meter 1: 118.2 kg/h
Temp sensor for low-pressure EGR after cooler: raw value: 103.3 °C
Outside air temperature: 16.5 °C
Intake air temperature before throttle valve: calculated: 25.3 K
Calculated temperature of compressor wall: 76.7 °C

5552 - Intake Air Temp. Sensor (G42)
P0111 00 [232] - Implausible Signal
MIL ON - Intermittent - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 3
Mileage: 151398 km
Date: 2017.02.02 (Thursday Morning)
Time: 06:43:17

Engine speed: 0.00 /min
Normed load value: 0.0 %
Vehicle speed: 0 km/h
Coolant temperature: 3 °C
Intake air temperature: 37 °C
Ambient air pressure: 1000 mbar
Temp sensor for low-pressure EGR after cooler: raw value: -0.9 °C
Action:
Ran Ross VCDS scan
Ordered new MAP sensor after google, TDIClub forum searches

Saturday,18,February,2017,11:21:46:12876
(Scan truncated)
12642 - Charge Air Cooler
P026A 00 [237] - Efficiency Below Threshold
MIL ON - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 152434 km
Date: 2017.02.13 (Monday mid day)
Time: 11:29:13

Engine speed: 1586.50 /min
Normed load value: 0.0 %
Vehicle speed: 85 km/h
Coolant temperature: 86 °C
Intake air temperature: 49 °C
Ambient air pressure: 990 mbar
Air mass at air mass meter 1: 117.0 kg/h
Temp sensor for low-pressure EGR after cooler: raw value: 78.8 °C
Outside air temperature: 7.0 °C
Intake air temperature before throttle valve: calculated: 25.5 K
Calculated temperature of compressor wall: 66.7 °C

5552 - Intake Air Temp. Sensor (G42)
P0111 00 [237] - Implausible Signal
MIL ON - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 152407 km
Date: 2017.02.13 (Monday Morning)
Time: 06:45:46

Engine speed: 0.00 /min
Normed load value: 0.0 %
Vehicle speed: 0 km/h
Coolant temperature: 1 °C
Intake air temperature: 45 °C
Ambient air pressure: 990 mbar
Temp sensor for low-pressure EGR after cooler: raw value: 1.2 °C



Action:
Wiped off sensor, sprayed down with Sea Foam and compressed air. Lubricated o-ring with dielectric grease, and re installed.

[jw4free]

Saturday,25,February,2017,15:52:51:12876
(Scan truncated)
12642 - Charge Air Cooler
P026A 00 [237] - Efficiency Below Threshold
MIL ON - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 153213 km
Date: 2017.02.19
Time: 11:21:21

Engine speed: 1945.00 /min
Normed load value: 52.2 %
Vehicle speed: 102 km/h
Coolant temperature: 97 °C
Intake air temperature: 66 °C
Ambient air pressure: 980 mbar
Air mass at air mass meter 1: 119.1 kg/h
Temp sensor for low-pressure EGR after cooler: raw value: 92.0 °C
Outside air temperature: 19.0 °C
Intake air temperature before throttle valve: calculated: 24.0 K
Calculated temperature of compressor wall: 74.9 °C

5552 - Intake Air Temp. Sensor (G42)
P0111 00 [237] - Implausible Signal
MIL ON - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 153189 km
Date: 2017.02.19
Time: 10:01:01

Engine speed: 0.00 /min
Normed load value: 0.0 %
Vehicle speed: 0 km/h
Coolant temperature: 12 °C
Intake air temperature: 63 °C
Ambient air pressure: 980 mbar
Temp sensor for low-pressure EGR after cooler: raw value: 13.3 °C

Actions:
Ran Ross VCDS Scan
Cleared Codes
Pulled 03G 906 051E
Note: Greenish oil/water froth (less than previous, but still apparent)



Voltage check: 0 281 002 9770 281 002 976
OldNew
1-4 1.54 kOhm1.61kOhm
1-3 3.14 kOhm3.26 kOhm
1-2 0.46 kOhm 2.95 kOhm
2-3 3.60 kOhm6.17 kOhm
2-4 2.01 kOhm4.44 kOhm
3-4 1.59 kOhm1.65 kOhm

Speculation: oil/water condensation froth creeps into the sensor and decreases resistance, and causes IAT Portion of sensor to read “Implausible Signal”. This in turn causes the P026A code as the computer suspects the intercooler is compromised.

Note: 03G 906 051E = 0 281 002 977 = 0 281 002 976
Absolute pressure sensor 50-XXX kPa with integrated air temperature sensor. Supply voltage 5V. Bosch compact connector. Pin =1 Ground, Pin 2 =NTC (Temp), Pin 3 =+5 V, Pin 4 =Output signal. Vacuum connection: O-ring

Replaced with New sensor 0 281 002 976 (bought thru e-bay: less than $50)

So Far So Good.

[VeeDubTDI]

Good post! Thanks.