P0546 2.7HDI hard to tell which temperature sensor fault it is

[kbosak]

Peugeot 407 coupe JUHZJ 2006.
Looking at
Model 407 Body: COUPE 2 DOORS / Engine: 2.7 HDi particle emission filter mechanical emission control REGULATOR BOX EXH TEMP PROBE
https://catalogs.ssg.asia/peugeot/?lang ... aWVyPT0%3D

The error P0546 “Exhaust Gas Temperature Sensor Circuit High Bank 1 Sensor 1.”
Is in fact not very clear which temp sensor is concerned and there are FOUR in total around exhaust system!
Various sources (forum guesses) indcated this is about pre-catalyser temp probe issue, but nobody confirmed it in convincing way.
Meanwhile I have changed post-catalyser temp probe as precautiionary measure (somebody been tamperting with).

So now I have problems accessing and diagnosing which one is it:
PART1 1618.F7 (front? rear already replaced...)
or maybe
PART2 1628.RX (replaceable by 1618LW)
or maybe
PART3 1618.76

mechanics have secured one cable on one of them, now we are discussing which one is really which. All remaining sensors are 'welded on' so it is hard to tell whcih is wrong. The error is not just popping up immediately, one have practically reach DPF regen conditions to see it.

[RichardW]

If you unplug the sensors then you should get a circuit fault which should then allow you to work out which is which?

[kbosak]

The problem is those sensors seem to map in pairs and generate one or more faults. For example rear one (postcat) was completely broken... and generated no faults.

[kbosak]

https://www.forum-peugeot.com/Forum/thr ... hdi.81242/
This suggests
"P0546 Signal température amont précata arrière"
This is rear temp sensor before catalysator.
This suggests according to
https://catalogs.ssg.asia/peugeot/?lang ... aWVyPT0%3D
1618 LW

[kbosak]

Same question posted here by somebody else
https://www.andre-citroen-club.de/forum ... rsensoren/

[kbosak]

Also here
https://www.andre-citroen-club.de/forum ... rem-teuer/
https://www-andre--citroen--club-de.tra ... r_pto=wapp