P20D1Exhaust Aftertreatment Fuel Injector B Control 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
- Injector B is a second exhaust fuel doser, found only on layouts with two dosing points, for example twin exhaust paths. This code reports a broken control line or open coil on that second unit. No manufacturer documents P20D1 publicly; the logic would mirror injector A, where GM's diesel tables look for an off-state output voltage stuck in a mid band (P20CB, Type B). CARB wants every electrical part of an in-exhaust injection system covered by the comprehensive component checks. Most single-doser engines never set it, and many car diesels heat the filter by late in-cylinder injection instead of a doser at all.
- What you may notice
- Check engine light on
- Regeneration incomplete on the affected exhaust path
- Likely causes
- LikelyLoose or corroded connector at doser B
- PossibleBroken wire to doser B
- RareOpen solenoid winding in doser B
- 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 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.