Powertrain
generic / SAE
P248B
Reductant Heater A Sense Circuit High
Same as P248A with the sense voltage above the plausible range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number4 / 8B
Possible causes
- Sense line shorted to supply high
- Connector pins corroded - high contact resistance low
- Supply wire pinched against B+ source low
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)
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 200–700 €
- Estimated time: 1–3 h
- Component: reductant heater a
- MIL / check engine light
- emissions-relevant
Sources
References
sae:J2012