P20DAExhaust Aftertreatment Fuel Supply Control Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- For the supply valve ahead of the exhaust doser, the control line reads too high, typically because it touches battery voltage or, on some drivers, an open line pulled up internally. Volvo and Mack log it as P20DA00 and list it in guide KC-2157 among the AHI module electrical faults, with the instruction to check that module's wiring and connector. A circuit stuck high leaves the valve unable to follow commands, so the control unit stops dosing and active regeneration is lost until the fault is repaired. Its siblings are P20D7 (line broken) and P20D9 (line grounded); a mechanically stuck valve sets P20DB or P20DC.
- What you may notice
- Check engine light on
- Active regeneration not possible
- Likely causes
- LikelyValve control wire shorted to a powered line
- PossibleDamaged coil in the supply valve
- RareFaulty output stage in the control module
- 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: €100 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.