Powertrain
Definition only
Lights the check engine lamp
P2ACF: Reductant Temperature Sensor B Circuit High
Standardized SAE J2012 code · P2Axx codes
What does P2ACF mean?
Voltage on the reductant temperature B sensor signal line is above the expected window. Wire shorted to B+ or sensor open.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Common causes
- High Signal wire shorted to B+
- Medium Open sensor
- Low Connector pins corroded - high contact resistance
Likelihood is a general estimate across vehicles; your make and model may differ.
Add your car to see reports of P2ACF on the same make and model first.
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