MasterTuning Fault code dictionary (DTC)

P229F — Downstream NOx sensor: implausible signal

Severity: Warning Can you drive? With caution: limp mode possible, have it checked soon Make: All makes (OBD-II standard)
MeaningThe sensor measuring nitrogen oxides after the catalyst is sending a value the ECU does not consider credible. It is one of the most common faults on Euro 6 diesels.
FamilyPowertrain (P)

Typical symptoms

Engine warning light on
AdBlue warnings
Reduced power on some models

Common causes

NOx sensor worn out by heat
Damaged wiring or water in the connector
Sensor control unit not answering on the bus

What to do

The NOx sensor is a wear item: needing one after a few years is normal. Check the wiring first, though, because a corroded connector produces exactly the same code at no cost.

Frequently asked questions

What does code P229F mean?

Downstream NOx sensor: implausible signal. The sensor measuring nitrogen oxides after the catalyst is sending a value the ECU does not consider credible. It is one of the most common faults on Euro 6 diesels.

Can I keep driving with code P229F active?

With caution: limp mode possible, have it checked soon

Common causes — P229F

NOx sensor worn out by heat Damaged wiring or water in the connector Sensor control unit not answering on the bus

How do you fix code P229F?

The NOx sensor is a wear item: needing one after a few years is normal. Check the wiring first, though, because a corroded connector produces exactly the same code at no cost.

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