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
2021 Ford Edge SE, 4WDSECTION Test Procedure
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2022 Ford F-550 Super Duty, 2022 Ford F-450 Super Duty, 2022 Ford F-350 Super Duty, 2022 Ford F-250 Super Duty, and 2021 Ford F-550 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.
- RF1 PRELIMINARY DIAGNOSIS
Are DTCs P204B, P204C, P204D, or P204E present?
Yes No GO to RF2. 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. - RF2 CHECK THE REDUCTANT PRESSURE SENSOR OPERATION
- Ignition ON, engine OFF.
- Access the PCM and monitor the REDUCT_TNK_P (PRESS) PID.
- Record the REDUCT_TNK_P PID value.
- Carry out the SCR Dosing Measurement Test on the scan tool.
- Record the REDUCT_TNK_P PID value.
Does the REDUCT_TNK_P PID value change from the initial recorded value?
Yes No 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. REFER to NO DIAGNOSTIC TROUBLE CODES (DTCS) PRESENT SYMPTOM CHART INDEX , if a driveability concern exists. GO to RF3. - RF3 CHECK THE REDUCTANT PRESSURE SENSOR CIRCUITS FOR AN OPEN
- Ignition OFF.
- Reductant Pump Assembly connector disconnected.
- PCM-T connector disconnected.
- Measure the resistance between:
(+) Reductant Pump Assembly Connector, Harness Side (-) PCM-T Connector, Harness Side RDP - Pin 4 RDP - Pin 40 VREF - Pin 5 VREF - Pin 68 SIGRTN - Pin 3 SIGRTN - Pin 55 Are the resistances less than 5 ohms?
Yes No GO to RF4. For DTC P204E, REPAIR the open circuit.
CARRY OUT the Selective Catalytic Reduction (SCR) System Procedure. REFER to DRIVE CYCLES . Clear the RDCM and PCM DTCs. REPEAT the self-test.
For all others, REPAIR the open circuit. Clear the RDCM and PCM DTCs. REPEAT the self-test. - RF4 CHECK THE REDUCTANT PRESSURE SENSOR CIRCUITS FOR A SHORT TO GROUND
- Measure the resistance between:
(+) Reductant Pump Assembly Connector, Harness Side (-) RDP - Pin 4 Ground VREF - Pin 5 Ground SIGRTN - Pin 3 Ground Are the resistances greater than 10K ohms?
Yes No GO to RF5. REPAIR the short circuit. Clear the RDCM and PCM DTCs. REPEAT the self-test. - RF5 CHECK THE REDUCTANT PRESSURE SENSOR CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition ON, engine OFF.
- Measure the voltage between:
(+) Reductant Pump Assembly Connector, Harness Side (-) RDP - Pin 4 Ground VREF - Pin 5 Ground SIGRTN - Pin 3 Ground Is any voltage present?
Yes No REPAIR the short circuit. Clear the RDCM and PCM DTCs. REPEAT the self-test. INSTALL a new Reductant Pump assembly. REFER to the appropriate Engine Emission Control article.
CARRY OUT the Selective Catalytic Reduction (SCR) System Procedure. REFER to DRIVE CYCLES . Clear the GPCM and PCM DTCs. REPEAT the self-test.
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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.