Ageing or contaminated downstream NOx sensor; Ammonia slip from excessive AdBlue dosing affecting the reading; Exhaust leak near the sensor; Faulty sensor control module or wiring.

NOx sensors

P229F NOx Sensor Circuit Range/Performance (Bank 1 Sensor 2)

Q: What does P229F mean?

NOx Sensor Circuit Range/Performance (Bank 1 Sensor 2). The downstream NOx sensor measures NOx after the SCR catalyst so the ECU can verify SCR efficiency. P229F is set when its signal is implausible or outside the expected range.

The downstream NOx sensor measures NOx after the SCR catalyst so the ECU can verify SCR efficiency. P229F is set when its signal is implausible or outside the expected range.

Common causes

Ageing or contaminated downstream NOx sensor
Ammonia slip from excessive AdBlue dosing affecting the reading
Exhaust leak near the sensor
Faulty sensor control module or wiring

Typical symptoms

Check engine light (MIL) on
SCR efficiency monitoring not completed
Countdown to engine start restriction on some vehicles

P229F and NuoVolta

If the SCR/AdBlue system and its NOx sensors have been removed for off-road or motorsport use, where permitted by law, the NuoVolta AdBlue / SCR / NOx Removal solution adjusts the ECU calibration and the DTC removal feature can disable this code. On a working system, test the sensor and check AdBlue dosing first.

AdBlue / SCR / NOx Removal Available for 121 ECUs

Related codes

P2200NOx Sensor Circuit (Bank 1 Sensor 1) P2201NOx Sensor Circuit Range/Performance (Bank 1 Sensor 1) P2BADNOx Exceedance - Root Cause Unknown

Diagnose and repair real faults first. Removing or disabling emission systems is only permitted where allowed by law, for example for off-road or motorsport use.