P20D8Exhaust Aftertreatment Fuel Supply Control Performance
- 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 supply valve ahead of the exhaust doser is electrically sound, but the pressure it produces in the feed line does not follow its commands. A typical layout, described in a patent assigned to International Engine, measures that line pressure and uses it both to meter the dose and to diagnose the regulating valve. Hino's J08E manual lists P20D8 among the codes to resolve before chasing a regeneration fault; its trucks use a fuel cut valve ahead of the dosing injector. CARB treats a supply that runs out of control authority as a feedback fault. Circuit faults are P20D7, P20D9 and P20DA; a valve fixed open or shut is P20DB or P20DC.
- What you may notice
- Check engine light on
- Regenerations take longer or fail
- Likely causes
- LikelySluggish or contaminated supply valve
- PossibleLow feed pressure from a clogged fuel filter or weak low-pressure pump
- RareLine pressure sensor reading off
- 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: €150 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.