Reductant Pump Motor Circuit
Problem with the reductant pump motor circuit.
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 reductant pump is used to move the diesel exhaust fluid (DEF) from the tank to the injection system. If there's an issue here, the pump might not be working like it should, which can stop the system from cleaning emissions properly.
What the computer is actually seeing
The electronic control unit (ECU) monitors the voltage and current from the reductant pump circuit. If the voltage drops below 5 volts or goes above the expected range during operation, it triggers code SPN 4757.
What a healthy reading looks like
The expected voltage for the pump circuit should be around 12-14 volts when the pump is active, with a current draw of about 2-3 amps.
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 fuse for the reductant pump circuit. Replace if blown and retest.
- 22. Inspect the wiring and connectors going to the reductant pump for damage or corrosion. Fix as needed.
- 33. Measure the voltage at the pump connector while the engine is running. It should be 12-14 volts when the pump is activated. If not, check wiring back to the ECU.
- 44. Check the current draw of the pump with a multimeter; it should be around 2-3 amps. If less or no draw, replace the pump.
- 55. If all checks are good and the issue persists, consider testing or replacing the ECM.
Common causes
- Wiring issues (broken wires, corroded connectors)
- Faulty reductant pump
- Blown fuse for the pump circuit
- Faulty ECM (Electronic Control Module)
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code present?
Driving is possible but may lead to reduced engine performance and increased emissions. Fix it soon.
Will this code come back after fixing?
If all faulty components are replaced and wiring is repaired, it shouldn't return.
Why does this code appear with others?
It commonly pairs with related reductant system codes due to interconnected components.
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