What it means
The control module detects that reductant pump B remains on when it should be off. It sets the code when the pump control state or circuit feedback indicates unintended operation.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The reductant system uses pump B to move DEF (AdBlue) from its supply toward the exhaust aftertreatment system. The control module monitors the pump command and circuit feedback; P215D sets when pump B appears to remain on after it has been commanded off.
Common causes
Most likely first.
- Pump relay contacts welded
- Carbon or debris buildup preventing free movement
- Component wear with age - mechanical play
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
How to diagnose it
- Check freeze-frame data and reductant-system scan data for the pump B command and any reported feedback when the fault occurred.
- Inspect pump B's connector and harness for moisture, corrosion, chafing, or a short that could keep it powered.
- With the system checked according to the manufacturer's safety procedure, determine whether pump B continues operating when the module commands it off.
- Test the pump B relay or control device for contacts that remain closed, and verify the control circuit against the manufacturer's specification.
- If electrical control is correct, inspect the pump for binding or contamination using the manufacturer's procedure.
Common fixes
- Repair a loose, corroded, or damaged pump B connector or wiring.
- Replace a relay with contacts that remain closed, if fitted and confirmed faulty.
- Remove contamination or restriction if the manufacturer's service procedure permits it.
- Replace pump B if it is mechanically sticking or fails its electrical tests.
- Repair the confirmed reductant pump control fault.
Can I keep driving?
The vehicle may remain drivable initially, but the warning can progress to an emissions-related no-start countdown and the system may fail an emissions inspection. Follow any displayed countdown and have the reductant fault diagnosed promptly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.