Code result
P22FF
SCR NOx Catalyst Inlet Temperature Too Low
High severity
What it means
The temperature sensor at the SCR catalyst inlet reports a value below the threshold needed for efficient ammonia conversion. Below roughly 180-200 °C the SCR cannot reduce NOx and reductant injection is suspended; if this is detected continuously the ECU sets the fault.
Is it safe to drive?
No — stop driving
This code points to a problem that can cause damage or affect safety. Avoid driving and have the vehicle diagnosed promptly.
Most likely causes
Temperature sensor drifts low or has shifted resistance
highOne of the most commonly reported causes for this code — check this first.
Short-trip operation - exhaust never reaches operating temperature
mediumA plausible cause — test and verify before replacing parts.
Exhaust heater or heat-management strategy not active
lowLess common, but worth ruling out after the more likely causes.
Related help
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