P20A0Reductant Purge Control Valve A Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- After the engine stops, many airless DEF systems suck the fluid out of the line and injector back into the tank so that nothing freezes there. In Bosch's Denoxtronic 2.2 this is done by a 4/2-way valve in the supply module that reverses the flow. P20A0 concerns the drive circuit of this valve, chiefly an interruption. GM checks it on the 6.6 L Duramax (LML/LGH) with the driver switched off: an impedance above 200 kΩ between ECM pin and load for 3 s sets the code, Type A. Volkswagen, on the 2014 Touareg 3.0 TDI (CNRB), uses a power-stage voltage between 2.97 and 4.70 V. Shorts to ground and to power are split off as P20A2 and P20A3. If the line cannot be emptied, DEF may stay in the injector and line and freeze there in winter.
- What you may notice
- MIL on (GM Type A, first trip)
- DEF system or emission service message
- Risk of frozen DEF line or injector in winter
- Likely causes
- LikelyCoil of the purge or reversing valve open
- LikelyConnector at the supply module loose or corroded by DEF
- PossibleWire to the valve broken
- RareOutput stage in the engine or dosing control unit defective
- 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 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.