P20D6 code meaning
Exhaust Aftertreatment Fuel Injector B Stuck Closed
Powertrain system Generic code P20xx codes Check engine light
What P20D6 means
The second exhaust fuel doser (B) fails to deliver fuel even though the control unit commands it open. No manufacturer documents P20D6 publicly. For doser A, Volvo and Mack handle the matching code P20D0 by checking the dosing module and replacing the nozzle, whose tip tends to clog with carbon; the same weak spot applies to B. A blocked doser means the catalyst stays too cool for regeneration, so soot keeps accumulating in the filter until power is cut back. CARB requires a malfunction once the injection system cannot achieve regeneration. Stuck open on the same doser is P20D5.
P20D6 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P20D6
- Check engine light on
- Failed or frequent regenerations
- Reduced power once the filter is heavily loaded
Common causes of P20D6
- Most likelyClogged nozzle tip on doser B
- PossibleNo fuel reaching doser B because of a blocked line or closed supply valve
- Less likelyMechanically seized valve in doser B
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Aftertreatment fuel injector
What each part of P20D6 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 0 | Area: fuel and air metering and auxiliary emission controls. |
| D6 | The exact fault in that area. |
What to do next
- Note P20D6 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P20D6
What does P20D6 mean?
P20D6 means "Exhaust Aftertreatment Fuel Injector B Stuck Closed". The second exhaust fuel doser (B) fails to deliver fuel even though the control unit commands it open. It is a generic code, so it means the same on every make.
Is it safe to drive with P20D6?
Drive gently and only to a workshop. With P20D6 the car can go into limp mode (reduced power) to protect itself.
Will P20D6 fail an emissions test?
Yes, it can. P20D6 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P20D6 to fix?
Difficulty: hard. A typical repair takes 1 to 3 hours of work. This is a job for a workshop.
Will P20D6 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.