Code result
P229F
NOx Sensor Circuit Range/Performance Bank 1 Sensor 2
High severity
What it means
The downstream NOx sensor on bank 1 (after the SCR catalyst) returns implausible NOx readings during operation. Either the sensor is degraded or upstream chemistry is abnormal.
Is it safe to drive?
No — stop driving
This code can put the vehicle into limp or reduced-power mode. Avoid extended driving and have the vehicle diagnosed promptly.
Most likely causes
NOx sensor aging
highOne of the most commonly reported causes for this code — check this first.
Low SCR efficiency
mediumA plausible cause — test and verify before replacing parts.
Sensor element aged beyond calibration window
lowLess common, but worth ruling out after the more likely causes.
Related help
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