P20D5Exhaust Aftertreatment Fuel Injector B Stuck Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- The second exhaust fuel doser (B) keeps passing fuel after it has been told to shut. No manufacturer documents P20D5 publicly; for the single doser A, Volvo and Mack trace the equivalent code P20CF to the fuel supply or the dosing module, and Ram fixed it on Cummins pickups with software. Detection usually relies on pressure in the doser feed line not rising again after closing, or on unexplained heat across the catalyst. Raw diesel in a hot catalyst can overheat it and causes smoke and fuel smell. CARB requires such injection faults to be caught. The stuck-closed counterpart is P20D6.
- What you may notice
- Check engine light on
- White smoke or fuel smell
- Higher fuel consumption
- Likely causes
- LikelyDeposits keeping doser B from sealing
- PossibleUpstream shutoff valve leaking fuel through
- RareCalibration error in the control software
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €200 – €2,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.