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
- W1 CHECK FOR PERFORMANCE MODIFICATIONS OR AIR FLOW CONCERNS NOTE: Diagnose any intake air system component, exhaust system component or VREF circuit DTCs before diagnosing EGR DTCs.
- Ignition OFF.
- Visually inspect the vehicle for aftermarket accessories and performance modifications (air filter, exhaust system, intake system, performance chip, turbocharger). Refer to ENGINE CONTROL (EC) SYSTEM , Modifications to OBD Vehicles.
- Check the intake air system (air cleaner, housing, ductwork) for obstructions or blockage.
- Check for broken or loose air outlet tube clamps (throttle body and air cleaner assembly ends), cracks or holes in the air outlet tube, and worn gaskets between the MAF sensor and the air cleaner assembly.
- Check the crankcase ventilation system for leaks and restrictions.
- Check the charge air cooler (CAC) system for leaks and restrictions.
- Check the exhaust system obstructions, blockage or leaks (soot trails).
Are any concerns present?
Yes No REPAIR as necessary.
Clear the PCM DTCs. REPEAT the self-test.GO to W2. - W2 CHECK FOR AN INTERMITTENT CONCERN
- Ignition ON, engine OFF.
- Access the PCM and monitor the EGRVP (VOLT) PID.
- While observing the PID for voltage spikes, wiggle, shake, and bend small sections of the wiring harness while working from the EGR valve to the PCM.
Is the voltage between 0.3 - 0.7 V (F-150) or 0.49 - 1.25 V (all others)?
Yes No GO to W3. REPAIR as necessary.
Clear the PCM DTCs. REPEAT the self-test. - W3 CHECK FOR VOLTAGE BETWEEN THE VREF AND SIGRTN CIRCUITS
- Ignition OFF.
- EGR Valve connector disconnected.
- Ignition ON, engine OFF.
- Measure the voltage between:
(+) EGR Valve Connector, Harness Side (-) EGR Valve Connector, Harness Side VREF SIGRTN Is the voltage between 4.5 - 5.5 V?
Yes No GO to W4. GO to PINPOINT TEST B . - W4 CHECK THE EGR VALVE HARNESS FOR AN OPEN
- Ignition OFF.
- PCM-E connector disconnected.
- Measure the resistance between:
(+) EGR Valve Connector, Harness Side (-) PCM-E Connector, Harness Side EGR EGR EGRVCL EGRVCL EGRVCH EGRVCH Are the resistances less than 5 ohms?
Yes No GO to W5. REPAIR the open circuit. Clear the PCM DTCs.
REPEAT the self-test. - W5 CHECK THE EGR VALVE HARNESS FOR A SHORT TO GROUND
- Measure the resistance between:
(+) EGR Valve Connector, Harness Side (-) EGR Ground EGRVCH Ground EGRVCL Ground Are the resistances greater than 10K ohms?
Yes No GO to W6. REPAIR the short circuit. Clear the PCM DTCs.
REPEAT the self-test. - W6 CHECK THE EGR VALVE HARNESS FOR A SHORT TO VOLTAGE
- Ignition ON, engine OFF.
- Measure the voltage between:
(+) EGR Valve Connector, Harness Side (-) EGR Ground EGRVCL Ground EGRVCH Ground Is any voltage present?
Yes No REPAIR the short circuit. Clear the PCM DTCs.
REPEAT the self-test.GO to W7. - W7 CHECK FOR THE EGRVCH AND EGRVCL CIRCUITS SHORTED TOGETHER
- Ignition OFF.
- Measure the resistance between:
(+) EGR Valve Connector, Harness Side (-) EGR Valve Connector, Harness Side EGRVCH EGRVCL Is the resistance greater than 10K ohms?
Yes No GO to W8. REPAIR the short circuit. Clear the PCM DTCs.
REPEAT the self-test. - W8 CHECK THE INTERNAL RESISTANCE OF THE EGR VALVE CONTROL MOTOR NOTE: Not all PIDs are available on all vehicles.
- Measure the resistance between:
(+) EGR Valve Connector, Component Side (-) EGR Valve Connector, Component Side EGRVCH EGRVCL - Access the PCM and monitor the MAFLRN_IDLE (NUM) PID.
- Access the PCM and monitor the MAFLRN_AIDLE (NUM) PID.
- Record the PID values.
Is the resistance between 1 - 900 ohms?
Yes No For DTCs P0401 and P2457, GO to PINPOINT TEST AZ .
For F-650/F-750 and F-Series Super Duty with DTCs P0403, P0404, P0405, P0406, P0489 or P0490, GO to W18.
For Transit Connect, GO to W10.
For all others, GO to W9.For F-150, with MAFLRN_AIDLE values between -0.06 and 0.06, INSTALL a new EGR valve. REFER to the appropriate Engine Emission Control article. Clear the PCM DTCs. REPEAT the self-test.
For F-150, with MAFLRN_AIDLE values less than -0.06 or greater than 0.06, INSTALL a new EGR valve. REFER to the appropriate Engine Emission Control article. CARRY OUT the Reset And Clear The Specified Function MAF Sensor on the scan tool. REFER to CLEAR THE CONTINUOUS DIAGNOSTIC TROUBLE CODES (DTCS) AND RESET THE EMISSION MONITORS INFORMATION IN THE POWERTRAIN CONTROL MODULE (PCM) . Clear the PCM DTCs. REPEAT the self-test.
For all others, with MAFLRN_IDLE and MAFLRN_AIDLE values between 0.00 and 0.12, INSTALL a new EGR valve. REFER to the appropriate Engine Emission Control article. Clear the PCM DTCs. REPEAT the self-test.
For all others, INSTALL a new EGR valve. REFER to the appropriate Engine Emission Control article. CARRY OUT the Reset And Clear The Specified Function MAF Sensor on the scan tool.
REFER to CLEAR THE CONTINUOUS DIAGNOSTIC TROUBLE CODES (DTCS) AND RESET THE EMISSION MONITORS INFORMATION IN THE POWERTRAIN CONTROL MODULE (PCM) . Clear the PCM DTCs. REPEAT the self-test. - Measure the resistance between:
- W9 CHECK THE EGR VALVE POSITION VALUES NOTE: Not all PIDs are available on all vehicles.
- Ignition OFF.
- EGR Valve connector connected.
- PCM-E connector connected.
- Ignition ON, engine OFF.
- Access the PCM and monitor the EGRVP (VOLT) PID.
- Monitor the EGRVP PID and compare the values to the EGR valve position sensor table.
- Access the PCM and control the EGRVPDES (PER) PID.
- Decrease the commanded PID to the minimum value.
- Increase the commanded PID to the maximum value.
EGR Valve Position Sensor (Approximate)
EGR Command EGR V Minimum EGR V Maximum 0% 0.4 V (F-150) 0.92 V (F-650/F-750 and F-Series Super Duty) 0.68 V (all others) 0.6 V (F-150) 1.07 V (F-650/F-750 and F-Series Super Duty) 1.14 V (all others) 60% (F-150) 65% (F-650/F-750 and F-Series Super Duty) 70% (all others) 2.75 V (F-150) 3.14 V (F-650/F-750 and F-Series Super Duty) 2.72 V (all others) 3.05 V (F-150) 3.23 V (F-650/F-750 and F-Series Super Duty) 3.35 V (all others) - Access the PCM and monitor the MAFLRN_IDLE (NUM) PID.
- Access the PCM and monitor the MAFLRN_AIDLE (NUM) PID.
- Record the PID values.
Does the PID value approximately match the values in the EGR valve position sensor table?
Yes No GO to W10. For F-150, with MAFLRN_AIDLE values between -0.06 and 0.06, INSTALL a new EGR valve. REFER to the appropriate Engine Emission Control article. Clear the PCM DTCs. REPEAT the self-test.
For F-150, with MAFLRN_AIDLE values less than -0.06 or greater than 0.06, INSTALL a new EGR valve. REFER to the appropriate Engine Emission Control article. CARRY OUT the Reset And Clear The Specified Function MAF Sensor on the scan tool. REFER to CLEAR THE CONTINUOUS DIAGNOSTIC TROUBLE CODES (DTCS) AND RESET THE EMISSION MONITORS INFORMATION IN THE POWERTRAIN CONTROL MODULE (PCM) . Clear the PCM DTCs. REPEAT the self-test.
For all others, INSTALL a new EGR valve. REFER to the appropriate Engine Emission Control article. CARRY OUT the Reset And Clear The Specified Function MAF Sensor on the scan tool.
REFER to CLEAR THE CONTINUOUS DIAGNOSTIC TROUBLE CODES (DTCS) AND RESET THE EMISSION MONITORS INFORMATION IN THE POWERTRAIN CONTROL MODULE (PCM) . Clear the PCM DTCs. REPEAT the self-test. - W10 CHECK THE OPERATION OF THE EGR VALVE WITH THE IGNITION ON ENGINE OFF NOTE: Not all PIDs are available on all vehicles.
- Ignition ON, engine OFF.
- Access the PCM and monitor the EGR_A_ACT (PER) PID.
- Access the PCM and control the EGRVPDES (PER) PID.
- Decrease the commanded PID duty cycle to the minimum value.
- Monitor the EGR valve position PID value while incrementing the commanded PID from the minimum value to the maximum value and back to the minimum value.
- Access the PCM and monitor the MAFLRN_IDLE (NUM) PID.
- Access the PCM and monitor the MAFLRN_AIDLE (NUM) PID.
- Record the PID values.
Is the EGR valve position PID value within 15% of the commanded PID value at all of the increments?
Yes No For Transit Connect, GO to W16.
For all others, GO to W11.For F-150, with MAFLRN_AIDLE values between -0.06 and 0.06, INSTALL a new EGR valve. REFER to the appropriate Engine Emission Control article. Clear the PCM DTCs. REPEAT the self-test.
For F-150, with MAFLRN_AIDLE values less than -0.06 or greater than 0.06, INSTALL a new EGR valve. REFER to the appropriate Engine Emission Control article. CARRY OUT the Reset And Clear The Specified Function MAF Sensor on the scan tool. REFER to CLEAR THE CONTINUOUS DIAGNOSTIC TROUBLE CODES (DTCS) AND RESET THE EMISSION MONITORS INFORMATION IN THE POWERTRAIN CONTROL MODULE (PCM) . Clear the PCM DTCs. REPEAT the self-test.
For all others, INSTALL a new EGR valve. REFER to the appropriate Engine Emission Control article. CARRY OUT the Reset And Clear The Specified Function MAF Sensor on the scan tool.
REFER to CLEAR THE CONTINUOUS DIAGNOSTIC TROUBLE CODES (DTCS) AND RESET THE EMISSION MONITORS INFORMATION IN THE POWERTRAIN CONTROL MODULE (PCM) . Clear the PCM DTCs. REPEAT the self-test. - W11 CHECK FOR INPUT SENSOR BIAS
- Ignition ON, engine OFF.
- Access the PCM and monitor the BARO (PRESS) and EBP (PRESS) PIDs.
Is the EBP within 7.5 KPa (1.09 psi) of the BARO PID reading?
Yes No GO to W15. INSTALL a new EP sensor. REFER to the appropriate Electronic Engine Controls article.
Clear the PCM DTCs. REPEAT the self-test. - W12 CHECK THE OPERATION OF THE MAF SENSOR WITH THE ENGINE RUNNING NOTE: Verify the engine oil temperature (EOT) is greater than 60°C (140°F) before testing.
- Ignition ON, engine running.
- Access the PCM and monitor the EOT (TEMP) PID.
- Access the PCM and monitor the MAF (FLOW) PID.
- Access the PCM and control the VGTDC (PER) PID.
- Command the VGTDC PID to 100%.
- Access the PCM and control the RPMDSD (RPM) PID.
- Increase the commanded engine speed to 1, 800 RPM using output state control.
- Access the PCM and control the EGRVPDES (PER) PID.
- Decrease the commanded EGR duty cycle to 0%.
Is the MAF PID greater than 0.08 kg/s (80 g/s) at sea level or 0.058 kg/s (58 g/s) at 10, 000 feet above sea level?
Yes No GO to W13. INSTALL a new MAF/IAT sensor. REFER to the appropriate Electronic Engine Controls article.
CARRY OUT the Reset And Clear The Specified Function MAF Sensor on the scan tool. REFER to CLEAR THE CONTINUOUS DIAGNOSTIC TROUBLE CODES (DTCS) AND RESET THE EMISSION MONITORS INFORMATION IN THE POWERTRAIN CONTROL MODULE (PCM) .
Clear the PCM DTCs. REPEAT the self-test. - W13 CHECK EGR VALVE OPERATION NOTE: Verify the engine oil temperature (EOT) is greater than 60°C (140°F) before testing.
- Ignition ON, engine running.
- Access the PCM and monitor the EOT (TEMP) PID.
- Access the PCM and monitor the MAF (FLOW) PID.
- Access the PCM and control the VGTDC (PER) PID.
- Command the VGTDC PID to 100%.
- Access the PCM and control the RPMDSD (RPM) PID.
- Increase the commanded engine speed to 1, 800 RPM using output state control.
- Access the PCM and control the EGRVPDES (PER) PID.
- Command the EGRVPDES PID to 40%.
Is the MAF PID greater than 0.035 kg/s (35 g/s) at sea level or 0.021 kg/s (21 g/s) at 10, 000 feet above sea level?
Yes No GO to W14. CHECK the EGR cooler bypass system for correct operation. REFER to Pinpoint Tests AZ: Exhaust Gas Recirculation (EGR) Cooler System . If OK, INSTALL a new EGR valve. REFER to the appropriate Engine Emission Control article.
CARRY OUT the Reset And Clear The Specified Function MAF Sensor on the scan tool. REFER to CLEAR THE CONTINUOUS DIAGNOSTIC TROUBLE CODES (DTCS) AND RESET THE EMISSION MONITORS INFORMATION IN THE POWERTRAIN CONTROL MODULE (PCM) .
Clear the PCM DTCs. REPEAT the self-test. - W14 CHECK EGR COOLER FLOW NOTE: Verify the engine oil temperature (EOT) is greater than 60°C (140°F) before testing.
- Ignition ON, engine running.
- Access the PCM and monitor the EOT (TEMP) and EGRTC (TEMP) PIDs.
- Access the PCM and monitor the MAF (FLOW) PID.
- Access the PCM and control the VGTDC (PER) PID.
- Command the VGTDC PID to 100%.
- Access the PCM and control the RPMDSD (RPM) PID.
- Increase the RPM_DSD PID to approximately 1, 800 RPM.
- Access the PCM and control the EGRVPDES (PER) PID.
- Command the EGRVPDES PID to 40%.
- Access the PCM and control the EGRCBV (MODE) PID.
- Command the EGRCBV PID ON, wait 5 seconds, then command the EGRCBV PID OFF.
- Monitor the MAF PID and the EGRTC PID values while commanding the EGRCBV PID from ON to OFF.
Does the MAF PID increase by less than 0.005 kg/s (5 g/s) and does the EGRTC PID decrease by more than 25° C (45.83°F)?
Yes No The system is operating correctly at this time.
RETURN to SYMPTOM CHARTS for further direction.GO to PINPOINT TEST AZ . - W15 CHECK THE OPERATION OF THE MAF/IAT SENSOR WITH THE ENGINE RUNNING NOTE: Not all PIDs are available on all vehicles.
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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.