Fabia II 1.6 TDi EGT Sensor faults

[Overdose]

I've just replaced sensor 3, but this was after the DPF and before the flexi joint and cat, sensor 4 seems to be the one after the cat. A rescan showed that sensor 3 now has a realistic temperature at cold, so this was definitely one of the problems. I've just got to see if I can get to sensor 4 on my own, otherwise it'll have to go to the garage and up on a ramp.
For info, sensor 3 giving a reading of 999C when cold, measured as open circuit.

[Crasher]

Sensor 3 is pre DPF, in the top right under your nose when you look in there

[Overdose]

That doesn't appear to be the case for my car, the only sensor before the DPF (ie the bit clamped to the turbo) is the oxygen sensor. I've replaced what I think is sensor 3, under and slightly to the left of the turbo and the figures on the scan are now good, so it must be sensor 3.
Interestingly, the DPF light has now come on, could this be because of a temperature mismatch between sensors 3 and 4?
I wonder if it would regenerate in this condition?
I guess I need to replace the other sensor and quick...

Edit: Given that sensor 3 and 4 are perhaps not in the same positions as your source of info suggests, is sensor 4 likely to be 03L906088 HL ? The HE suffix for sensor 3 seemed to be correct though, at least it's working.

What I need is item number 4 in the image attached.

sensor4.jpg

[mickeybo]

One of the things that are being over looked here the 3 sensors here are inter connecter they share the power & earthing & are using the same circuit as the coolant temperature sensor needs to be checked out

[Overdose]

Ok, thanks.

[Overdose]

The fix.

I have replaced both sensor 3 and 4 and the problem is now fixed, both sensors tested as open circuit.

For reference, I removed Pn 03L 906 088 DE from sensor position 3 (between DPF and cat) and replaced with Pn 03L 906 088 HE.
I removed Pn 03L 906 088 AF from sensor position 4 (after the cat) and replaced it with Pn 03L 906 088 HL.

I do not know if the DPF light came on because it needed a regen, but couldn't due to the EGT faults, or if the EGT faults themselves caused the light to come on (it might be the job of the DPF differential pressure switch to do this), but it went off after a 15 minute cruise at motorway speeds.

I hope this provides help for someone else.