P20A2Reductant Purge Control Valve A Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- The purge valve that reverses the DEF flow at shutdown is usually switched on the ground side. P20A2 reports that its control line is pulled too low, typically a short to ground somewhere between the driver and the coil, which would switch the valve on unintentionally or keep the driver from sensing it. GM tests the low-side driver of the 6.6 L Duramax with the output off and sets P20A2 when the impedance to controller ground is under 0.5 Ω for 2 s, Type A. Volkswagen flags the Touareg 3.0 TDI (CNRB, 2014) when the power-stage voltage falls below 2.97 V. Compared with P20A0, where the line is open, the fault here is an unwanted connection to ground. Chafed wiring near the tank and water in the connector are the usual findings; the controller may then block dosing.
- What you may notice
- MIL on at once (GM Type A)
- Service emission or DEF system message
- Dosing possibly disabled
- Likely causes
- LikelyControl wire chafed against the frame or tank bracket
- PossibleMoisture or DEF in the valve connector creating a leakage path
- RareValve coil shorted to its housing
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.