P246e bank 1 exhaust gas temperature sensor 4

[Crasher]

You will get a much better result by starting your own thread in the Golf 6 section rather than reviving a dead thread

[squowse]

2010 Passat B6 CAYC 1.6Tdi
I have just started having a flashing glow plug light constantly.
VCDS scan -
1 Fault Found:
14356 - Exhaust Gas Temperature Sensor 4 Bank 1
P246E 00 [173] - Electrical Malfunction
MIL ON - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 5
Mileage: 323492 km
Date: 2023.04.06
Time: 07:03:28


Engine RPM: 1435.25 /min
Normed load value: 45.9 %
Vehicle speed: 5 km/h
Coolant temperature: 14 °C
Intake air temperature: 11 °C
Ambient air pressure: 1000 mbar
Voltage terminal 30: 14.344 V
Unlearning counter according OBD: 40


Readiness: 0000 0000



A month ago the garage took off the DPF and sent it for cleaning. They also replaced the EGR valve.
From what I can tell, they will have removed this sensor? Or at least been working on or around it.
I'm guessing they have disturbed it? Or is it possible that this is coincidental?

Thanks

[Crasher]

That is the post DPF sensor, not a common failure but they don’t like being disturbed so probably not a coincidence but not their fault either.

[squowse]

Ok thanks. From what you said about thread stripping I don’t think its a job I want to attempt myself. Unless that was a different sensor?

[Crasher]

“Galling” as it is known is the name for a process called cold welding, where two metals fuse as they wipe against each other and the high grade stainless steel of the sensor and low grade stainless of the boss are prone to this so an EGT or Lambda sensor should always be removed with care and releasing fluid. The only way you know about how it feels is by (bad) experience, the sensation is the nut cracking free as per normal and then a few degrees in the sensation of it dragging and feeling rubbery is a tell tale so you stop and decide what to do. One approach is graphite based thin oil sprayed at the exposed thread and an induction heater ring around the boss, then tighten the sensor back in and then out, slowly (and with much chocking smoke), gently work the sensor out back and forth using heat and graphite spray, hopefully leaving the bosses thread in a condition where it can be “chased” with a tap and cutting paste such as ChemCut (not recommend for Vegetarians!) .On an A6 Ultra a few years ago, one of the sensor threads galled and we fitted a top quality aftermarket DPF with new sensors. After we had replaced the DPF under warranty FOUR times I gave up, dug the old DPF out of the scrap pile, welded in a new boss and it is still fine four years later. We now refuse to fit aftermarket DPF’s.