4124 - Sensor Reference Voltage B P0651 00 [172] - Open Circuit


New member
Hi - Golf Mk6 2.0L Tdi Match year 2011.

Its developed a fault flashing glow plug symbol and Engine fault light on and car goes into limp mode.

Vagcom scans and finds

1 Fault Found:
4124 - Sensor Reference Voltage B
P0651 00 [172] - Open Circuit
MIL ON - Intermittent - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 2
Mileage: 91158 km
Date: 2021.02.12
Time: 16:39:30

Engine RPM: 1572.00 /min
Normed load value: 43.9 %
Vehicle speed: 14 km/h
Coolant temperature: 54 °C
Intake air temperature: 10 °C
Ambient air pressure: 1020 mbar
Voltage terminal 30: 13.980 V
Unlearning counter according OBD: 40
Exhaust gas temperature sensor 1: 159.1 °C
Exhaust gas temperature sensor 2: -0.0 °C
Exhaust gas temperature sensor 3: 116.2 °C
Exhaust gas temperature sensor 4: 82.7 °C
Shut-off timer: last engine shut-off time: 305 s

Googling I find suggestion probable broken wire is cause.

But what is Sensor Reference Voltage B.......I believe this is suggesting a cable break in circuit B (circuit 2?) but how do I identify this?

At the moment I'm guessing just to look all over wiring loom everywhere for physical friction damage.....

Any advice or clues please.