P041FAIR System Switching Valve A Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- After a cold start the secondary air pump blows fresh air into the exhaust; switching valve A is the electrically driven valve that opens this path. GM checks the valve circuit in three codes – P0412 open, P041F shorted to ground, P044F shorted to positive – while other makers use P0413/P0414 or P0412 for everything. P041F means the control circuit is shorted to ground: GM checks with the driver switched off and sets the code at 0.5 Ω or less to ground (20 of 25 samples of 250 ms, above 11 V, MIL after two trips). The valve is then energised and open although not commanded; P0411 or P2440 may follow.
- What you may notice
- Check engine light on (after two trips)
- No change in driving
- Secondary air readiness not set, possibly P0411
- Likely causes
- LikelyControl wire chafed against ground
- PossibleWater or corrosion in the valve connector
- PossibleValve coil shorted to its housing
- RareDriver in the engine module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €30 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.