P20A6Reductant Injection Air Pressure Control Valve 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
- In an air-assisted DEF system the compressed air must reach the mixing point at a defined pressure, whether it comes from the vehicle's brake air supply or from a separate compressor. A solenoid valve sets or switches this air pressure. P20A6 marks an open circuit in its control: the controller commands the valve, but no current flows, so the atomizing air cannot be regulated. No manufacturer documents P20A6 publicly. Deutz, whose EMR L1 controller drives a similar air supply valve, files the open circuit under P2059 for the air pump or supply valve and under its own code P1062 for the air switching valve. Low and high faults of the same circuit are P20A8 and P20A9. Air-assisted dosing appeared with Bosch's Denoxtronic 1 in 2004 and was later replaced by airless systems.
- What you may notice
- SCR warning lamp or MIL on
- Dosing stops for lack of atomizing air
- Power derate on heavy vehicles
- Likely causes
- LikelySolenoid coil of the air pressure control valve open
- LikelyConnector unplugged or wire broken near the valve
- PossibleFuse or supply feed for the valve missing
- 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 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.