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DTC codes / P21xx · Fuel and air metering / P215D

P215DReductant Pump B Stuck On

P215D indicates that the engine control module has detected the reductant pump, which supplies diesel exhaust fluid to the selective catalytic reduction system, is stuck in the on position. The computer commands the pump off but continues to see voltage or current feedback indicating the pump is still running, which can lead to over-injection of reductant and potential system damage.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • A persistent or intermittent warning message on the dashboard regarding the emissions system
  • Possible reduction in engine power or limp mode if the fault escalates
  • Excessive diesel exhaust fluid consumption beyond normal levels
  • White or crystalline residue around the exhaust injector or tailpipe due to over-injection
  • Rough running or misfire in severe cases if reductant fouls the selective catalytic reduction catalyst

Common causes, most likely first

  1. Failed reductant pump relay that remains closed, supplying constant power to the pump
  2. Short circuit to voltage in the pump control wiring or connector
  3. Internal failure of the reductant pump motor or control module, causing it to stay energized
  4. Corroded or damaged electrical connectors at the pump or control module
  5. Faulty engine control module driver circuit that commands the pump on continuously
  6. Contaminated or frozen reductant fluid causing the pump to seize in the on position

How to diagnose and fix it

  1. Verify the fault with a scan tool by checking live data for reductant pump command and actual pump status
  2. Inspect the reductant pump relay and test it for proper operation, replacing if it sticks closed
  3. Check the wiring harness and connectors at the pump for signs of short circuits, corrosion, or damage
  4. Measure voltage and resistance at the pump connector to confirm whether the pump is receiving constant power
  5. Test the reductant pump directly by applying power and ground to confirm if it runs continuously without command
  6. If the pump is stuck on, replace the reductant pump assembly according to manufacturer procedures
  7. Clear the fault codes and perform a relearn or adaptation procedure if required, then verify the repair with a test drive

Before you replace the reductant pump

  • A stuck-closed reductant pump relay is a frequent culprit that is often overlooked because the pump itself tests fine when removed from the vehicle.
  • The code can set intermittently due to a wiring short that only occurs when the harness is flexed or exposed to heat, so a wiggle test of the harness is essential.
  • Some vehicles use a smart reductant pump with integrated electronics; a stuck-on condition may be caused by a software glitch that requires a module reflash rather than parts replacement.
  • Over-injection of diesel exhaust fluid can crystallize and block the selective catalytic reduction catalyst, leading to additional codes and costly repairs if not addressed promptly.
  • Do not assume the pump is defective solely based on this code; always verify the control circuit and relay operation first to avoid unnecessary parts swapping.

Can I keep driving with P215D?

You can usually drive the vehicle short distances to a repair facility, but avoid prolonged driving because continuous reductant injection can damage the selective catalytic reduction system and lead to more expensive repairs. If the vehicle enters limp mode or you notice excessive white smoke, stop driving and seek professional assistance.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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