P201F - Reductant Pump 'A' Stuck On
System
Powertrain (Engine & Gearbox)
Technical Description
The control module has detected a fault in the Reductant Pump 'A' Stuck On (P201F).
Multimeter Test Points & Nominal Values
| Test Point / Component | Measurement | Nominal Target Range | Test Condition |
|---|---|---|---|
| Reductant Pump 'A' Stuck On – Coil Resistance | Resistance (Ω) | 3 - 30 Ω (typical) | Connector disconnected at 20°C |
| Reductant Pump 'A' Stuck On – Duty Cycle | PWM (%) | 5 - 95 % (modulates with target) | Engine running, actuator in control |
| Reductant Pump 'A' Stuck On – Supply Voltage | Voltage (V) | 11.8 - 14.4 V | Ignition ON at connector |
Connector disconnected at 20°C
Engine running, actuator in control
Ignition ON at connector
Oscilloscope Waveform Analysis
2 ms/div, 20 V/divPossible Causes
Mechanical sticking or debris/carbon contamination jamming Reductant Pump 'A' Stuck On
Channel A:Verify dedicated wiring pins and signal pair for circuit A against the schematic.
Chafed or pinched wiring harness along the signal path to Reductant Pump 'A' Stuck On
Internal mechanical wear or carbon deposits inside Reductant Pump 'A' Stuck On
Defective internal output driver or reference circuit in the control module for Reductant Pump 'A' Stuck On
Symptoms
4
Recommended Solution
Compare signal voltage and resistance between circuit A and companion circuit B at module connector.
Remove component and inspect for carbon deposits or foreign debris preventing full mechanical closure.
Verify loaded supply voltage and harness terminal pins at Reductant Pump 'A' Stuck On.
Check circuit continuity and ground-side voltage drop (< 0.05 V) for Reductant Pump 'A' Stuck On.
Check supply and the low-side driver at the ECM connector. Replace the actuator or repair the circuit based on the readings.
Mechanic's Tip
Use the scan-tool output test with the scope on the control side at the same time. If duty changes but the actuator does not move, the valve is stuck — not the electrical fault you were chasing.