Powertrain
generic / SAE
P04A8
Exhaust Pressure Control Valve B Position Sensor Circuit Low
Same as P04A6 with the signal voltage below 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
GroupP0
Range / number4 / A8
Possible causes
- Signal shorted to ground high
- Connector pins corroded - high contact resistance low
- Harness chafing through insulation low
Inspection / repair
- Difficulty: medium
- DIY: possible
- Estimated cost: 150–500 €
- Estimated time: 0.8–2 h
- Component: exhaust pressure position sensor b
- MIL / check engine light
- emissions-relevant
Sources
References
sae:J2012