P20D5 code meaning
Exhaust Aftertreatment Fuel Injector B Stuck Open
Powertrain system Generic code P20xx codes Check engine light
What P20D5 means
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.
P20D5 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of P20D5
- Check engine light on
- White smoke or fuel smell
- Higher fuel consumption
Common causes of P20D5
- Most likelyDeposits keeping doser B from sealing
- PossibleUpstream shutoff valve leaking fuel through
- Less likelyCalibration error in the control software
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 P20D5 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. |
| D5 | The exact fault in that area. |
What to do next
- Note P20D5 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 P20D5
What does P20D5 mean?
P20D5 means "Exhaust Aftertreatment Fuel Injector B Stuck Open". The second exhaust fuel doser (B) keeps passing fuel after it has been told to shut. It is a generic code, so it means the same on every make.
Is it safe to drive with P20D5?
Drive gently and only to a workshop. With P20D5 the car can go into limp mode (reduced power) to protect itself.
Will P20D5 fail an emissions test?
Yes, it can. P20D5 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 P20D5 to fix?
Difficulty: hard. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will P20D5 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.