Strange obd code

[Paul heald]

Hi originally had code P2207 Nox sensor heater control circuit high bank 1. Changed nox sensor. Now got code U1535pl Manufacturer controller which I can't find any record of anywhere.
Any ideas?

[GiveMeABreak]

My initial feelings are with the first fault (P2207), that this requires both an engine management ECU software update and replacement of the NOx sensor and / or the electrical harness - depending on the results of the checks.

The U1535 code is related and whilst in operation, the following functions are in effect:

• Inhibiting of the deNOx catalytic converter protection function
• Inhibiting of the particle filter diagnostics
• Deactivation of the urea solution injection regulation
• Deactivation of oxygen sensor regulation
• Deactivation of the richness regulation in change to open loop

Suspect areas: Engine management ECU, Electrical harness, Connectors, NOx sensor, DeNOx system relay, Urea pump - gauge module.

It was an issue on some earlier vehicles with the Adblue system that the pumps failed requiring a new tank (as these are sealed units). I'm not saying this is the case in your situation, but I would get the dealer to check it out - for the charge of the diagnostic, they should be able to download an ECU update if it is required. If it is the tank, you may be able to get a good will gesture from Citroen if it is just out of warranty - but that will depend on whether it has been regularly serviced to manufacturer requirements.

[wheeler]

When the NOx sensor was replaced was the car told it has a new sensor fitted?
This has to be done with diagbox (or another suitable diag kit) when a new sensor is fitted.

[Paul heald]

Unfortunately I don't have the equipment to do the reprogram so will book it in at local garage to sort. Thanks