Reductant Metering Pump A Control Circuit/Open
The control circuit for the reductant metering pump has an open condition.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The computer can't send signals to the reductant (urea) pump, meaning the system can't inject the fluid needed for emissions control, leading to elevated emissions.
What the computer is actually seeing
The Engine Control Module (ECM) monitors the voltage in the control circuit of the reductant metering pump. It expects a voltage typically between 0.5 and 4.5 volts, but detects an open circuit (no voltage).
What a healthy reading looks like
Voltage should be between 0.5-4.5 volts when the pump is commanded to operate.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check the physical condition of the wiring and connectors to the reductant metering pump for damage or corrosion. Decision: If damaged, repair or replace wiring/connectors; if fine, proceed to step 2.
- 22. Measure the voltage at the pump connector while the engine is running and the system is active. Expected: 0.5-4.5 volts. Decision: If correct, the pump is likely faulty; if none, continue to step 3.
- 33. Inspect the ECM connector and harness for any issues. Look for bent pins or corrosion. Decision: Repair any found issues; if fine, go to step 4.
- 44. Check for any related codes that could indicate a broader issue with the ECM or other circuits. Decision: If other codes are present, address them first before assuming the ECM is faulty; if not, replace the reductant metering pump.
Common causes
- Open or shorted wire in the pump control circuit
- Defective reductant metering pump
- Faulty ECM
- Corroded connectors
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
No, continuing to drive can lead to higher emissions and potential damage to the catalytic system.
Will the code come back after repairs?
If all faults and wiring issues are properly addressed, the code should not return.
Why does this code pair with P20D6?
P20D6 indicates a specific issue in the reductant injection system, which often occurs due to the same wiring or pump problems that trigger P20D8.
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