Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Test Procedure
- RE1 PRELIMINARY DIAGNOSIS
Are DTCs P20A0, P20A2 or P20A3 present?
Yes No GO to RE2. Unable to duplicate the condition. CHECK for a loose connection, and damaged or corroded terminals. WIGGLE the harness attempting to recreate the concern. REPAIR as necessary.
RETURN to SYMPTOM CHARTS for further direction. - RE2 CHECK THE REDUCTANT PURGE VALVE SOLENOID RESISTANCE
- Ignition OFF.
- Reductant Purge Valve connector disconnected.
- Measure the resistance between:
(+) Reductant Purge Valve Connector, Component Side (-) Reductant Purge Valve Connector, Component Side RDPGC - Pin 1 VPWR - Pin 2
Is the resistance between 9.72 - 11.88 ohms?
Yes No GO to RE3. INSTALL a new Reductant Pump assembly. REFER to the appropriate Engine Emission Control article.
Clear the RDCM and PCM DTCs. REPEAT the self-test. - RE3 CHECK THE REDUCTANT PURGE VALVE SOLENOID FOR INTERNAL SHORTS
- Measure the resistance between:
(+) Reductant Purge Valve Connector, Component Side (-) RDPGC - Pin 1 Ground
Is the resistance greater than 10K ohms?
Yes No GO to RE4. INSTALL a new Reductant Pump assembly. REFER to the appropriate Engine Emission Control article.
Clear the RDCM and PCM DTCs. REPEAT the self-test. - Measure the resistance between:
- RE4 CHECK THE VPWR CIRCUIT FOR VOLTAGE
- Ignition ON, engine OFF.
- Measure the voltage between:
(+) Reductant Purge Valve Connector, Harness Side (-) VPWR - Pin 2 Ground
Is the voltage greater than 10 V?
Yes No GO to RE5. REPAIR the open circuit.
Clear the RDCM and PCM DTCs. REPEAT the self-test. - RE5 CHECK THE RDPGC CIRCUIT FOR AN OPEN
- Ignition OFF.
- Reductant Dosage Control Module connector disconnected.
- Measure the resistance between:
(+) Reductant Purge Valve Connector, Harness Side (-) Reductant Dosage Control Module Connector, Harness Side RDPGC - Pin 1 RDPGC - Pin 94
Is the resistance less than 5 ohms?
Yes No GO to RE6. REPAIR the open circuit.
Clear the RDCM and PCM DTCs. REPEAT the self-test. - RE6 CHECK THE RDPGC CIRCUIT FOR A SHORT TO GROUND
- Measure the resistance between:
(+) Reductant Purge Valve Connector, Harness Side (-) RDPGC - Pin 1 Ground
Is the resistance greater than 10K ohms?
Yes No GO to RE7. REPAIR the short circuit.
Clear the RDCM and PCM DTCs. REPEAT the self-test. - Measure the resistance between:
- RE7 CHECK THE RDPGC CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition ON, engine OFF.
- Measure the voltage between:
(+) Reductant Purge Valve Connector, Harness Side (-) RDPGC - Pin 1 Ground
Is any voltage present?
Yes No REPAIR the short circuit.
Clear the RDCM and PCM DTCs. REPEAT the self-test.GO to RE8. - RE8 CHECK FOR CORRECT REDUCTANT PURGE VALVE OPERATION
- Reductant Purge Valve connector connected.
- Reductant Dosage Control Module connector connected.
- Ignition ON, engine OFF.
- Carry out the SCR Leak Test on the scan tool to pressurize the system.
- Access the DCU and monitor the REDUCT_TNK_P (PRESS) PID.
- Record the REDUCT_TNK_P PID value.
- Access the DCU and control the REDUCT_RV_DC (PER) PID.
- Command the PID duty cycle to 100%.
- Access the DCU and monitor the REDUCT_TNK_P (PRESS) PID.
Does the REDUCT_TNK_P PID value decrease?
| Yes | No |
|---|---|
| The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. |
INSTALL a new Reductant Pump assembly. REFER to the appropriate Engine Emission Control article. Clear the RDCM and PCM DTCs. REPEAT the self-test. |
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.