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Home >> Jeep >> 2025 >> Grand Cherokee Altitude, AWD >> Repair and Diagnosis >> Engine Performance >> System >> 3.6L - DTCS P0369 To P0430 >> DTC Troubleshooting >> P0404 EGR Position Sensor Performance >> Diagnostic Test

Diagnostic Test

  1. CHECK FOR ANY SERVICE BULLETINS OR PCM SOFTWARE UPDATES 
    1. Check for any applicable Service Bulletins or Flash updates related to the DTC.

      Are there any applicable Service Bulletins or Flash updates?

      Yes 

      No 

      • Go To Next Step
  2. READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR DTC TO RETURN 
    1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
    2. For future reference, with the scan tool, run and save a vehicle Scan Report and all related recorded data.
    3. With the scan tool, erase all DTCs.
    4. Turn the ignition off for a minimum of 10.0 seconds.
    5. Turn the ignition on.
    6. Using the When Monitored and Set Conditions above and recorded data, operate the vehicle in the conditions that set the DTC.
    7. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      • Go To  4

      No 

      • Go To Next Step
  3. CHECK THE VEHICLE'S REPAIR HISTORY 
    1. Check the history of the vehicle for previous EGR Valve performance related DTCs within the past 90 days.

      Does the repair history show that the vehicle was in dealership for a EGR Valve performance fault within the past 90 days?

      Yes, and the EGR Valve was cleaned during the previous visit 

      • Verify that the connector is completely connected. Check the connector terminals for any pushed out, corroded or spread terminals causing a poor or intermittent connection. If the connector is good, replace the EGR Valve Assembly in accordance with the Service Information. Refer to: VALVE, EXHAUST GAS RECIRCULATION (EGR), REMOVAL AND INSTALLATION . The EGR VALVE REPLACED routine must be performed after replacing or cleaning the EGR Valve to reset the zero learn position. Failure to do so will cause a false failure and the P1404 DTC to set. With the scan tool, perform the EGR VALVE REPLACED routine.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to: 3.6L - POWERTRAIN VERIFICATION TEST .

      Yes, and the EGR Valve was replaced during the previous visit 

      • Verify that the connector is completely connected. Check the connector terminals for any pushed out, corroded or spread terminals causing a poor or intermittent connection. If the connector is good, Clean the valve by running Mopar Combustion Chamber cleaner through the engine. The EGR VALVE REPLACED routine must be performed after replacing or cleaning the EGR Valve to reset the zero learn position. Failure to do so will cause a false failure and the P1404 DTC to set. With the scan tool, perform the EGR VALVE REPLACED routine. Test drive the vehicle and verify the DTC does not return. If the fault does not return, check the engine for any fuel or air handling issues that can cause excessive soot or carbon buildup in the engine.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to: 3.6L - POWERTRAIN VERIFICATION TEST .

      No 

      • Test complete. Verify that the connector is completely connected. Check the connector terminals for any pushed out, corroded or spread terminals causing a poor or intermittent connection. The EGR Valve may have been carbonated/sooted up temporarily. Clean the valve by running Mopar Combustion Chamber cleaner through the engine. The EGR VALVE REPLACED routine must be performed after replacing or cleaning the EGR Valve to reset the zero learn position. Failure to do so will cause a false failure and the P1404 DTC to set. With the scan tool, perform the EGR VALVE REPLACED routine. Test drive the vehicle and verify the DTC does not return.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to: 3.6L - POWERTRAIN VERIFICATION TEST .
  4. CHECK THE (F855) 5-VOLT SUPPLY CIRCUIT FOR PROPER VOLTAGE AT THE EGR SENSOR HARNESS CONNECTOR 
    1. Turn the ignition off.
    2. Disconnect the harness connector at the component of the circuit being tested. Note:  The ECU harness connector should still be connected during this test step.
    3. Turn the ignition on.
    4. Set the DVOM to measure DC voltage.
    5. Connect the negative lead of the DVOM to a known good ground.
    6. With the positive lead of the DVOM, measure the voltage of the circuit being tested at the component harness connector.
    7. If it is necessary to probe a terminal at a PCM harness connector, connect the GPEC Diagnostic Adapter [special tool # 10436] to the appropriate PCM harness connector.
      NOTE:

      The GPEC Diagnostic Adaptor can add up to 1.5 Ohms of resistance to the circuit. 

      NOTE:

      Normal operating voltage should be between 4.8 and 5.2 volts. 

      CAUTION:

      Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the GPEC Diagnostic Adaptor to perform the diagnosis.

      Does the circuit have the proper voltage present?

      Yes 

      • Go To Next Step

      No 

  5. ISOLATE AND CHECK THE EGR (K678) CONTROL (-) CIRCUIT FOR AN OPEN/HIGH RESISTANCE 

    Read the CIRCUIT LOAD TESTING PROCEDURE for information on building a simple load test tool, additional load testing information and alternative methods of load testing or voltage drop testing a circuit. Refer to CIRCUIT LOAD TESTING PROCEDURES .

    1. Turn the ignition off.
    2. Disconnect the EGR harness connector.
    3. Disconnect the PCM harness connector to isolate the Control circuit.
    4. Connect the positive lead of the load test tool to the positive side of the Battery (A).
      GC0174954Courtesy of CHRYSLER GROUP, LLC
    5. Using an approved back probe tool, connect the negative lead of the load test tool to the Control circuit at one of the harness connectors (B).
    6. Using an approved back probe tool and a fused jumper wire, connect the Control circuit to the negative side of the Battery or a known good ground at the other harness connector (C and D).
    7. The bulb on the load test tool should be illuminated and bright if there is no resistance in the circuit. Compare the brightness of the bulb in the load test tool to that of a direct connection to battery.
      NOTE:

      To verify with certainty that the circuit is good, perform a simple voltage drop test across the 3156 bulb of the load test tool. 

      NOTE:

      A 12-volt test light can be substituted for the load test tool, but only if the test light draws enough current to effectively load test the circuit. Many high impedance test lights draw very little amperage (less than 0.1 amps) and are not reliable to load test a circuit. To perform a proper load test of a circuit, the tool being used should draw more than approximately 0.75 amps. 

      Is the load test bulb illuminated and bright?

      Yes 

      • Go To Next Step

      No 

  6. ISOLATE AND CHECK THE EGR (K677) CONTROL (+) CIRCUIT FOR AN OPEN/HIGH RESISTANCE 

    Read the CIRCUIT LOAD TESTING PROCEDURE for information on building a simple load test tool, additional load testing information and alternative methods of load testing or voltage drop testing a circuit. Refer to CIRCUIT LOAD TESTING PROCEDURES .

    1. Turn the ignition off.
    2. Disconnect the EGR harness connector.
    3. Disconnect the PCM harness connector to isolate the Control circuit.
    4. Connect the positive lead of the load test tool to the positive side of the Battery (A).
      GC0174954Courtesy of CHRYSLER GROUP, LLC
    5. Using an approved back probe tool, connect the negative lead of the load test tool to the Control circuit at one of the harness connectors (B).
    6. Using an approved back probe tool and a fused jumper wire, connect the Control circuit to the negative side of the Battery or a known good ground at the other harness connector (C and D).
    7. The bulb on the load test tool should be illuminated and bright if there is no resistance in the circuit. Compare the brightness of the bulb in the load test tool to that of a direct connection to battery.
      NOTE:

      To verify with certainty that the circuit is good, perform a simple voltage drop test across the 3156 bulb of the load test tool. 

      NOTE:

      A 12-volt test light can be substituted for the load test tool, but only if the test light draws enough current to effectively load test the circuit. Many high impedance test lights draw very little amperage (less than 0.1 amps) and are not reliable to load test a circuit. To perform a proper load test of a circuit, the tool being used should draw more than approximately 0.75 amps. 

      Is the load test bulb illuminated and bright?

      Yes 

      • Go To Next Step

      No 

  7. CHECK THE EGR (K684) CONTROL (-) CIRCUIT VOLTAGE 
    1. Connect the ECU harness connectors.
    2. Disconnect the EGR harness connector.
    3. Measure the voltage on the EGR Control (-) circuit at the EGR harness connector.
    4. Turn the ignition on.

      Does the voltage increase towards battery voltage and return to approximately 1 volt?

      Yes 

      • Go To Next Step

      No 

  8. CHECK THE EGR VALVE FOR CARBON OR SOOT BUILD UP 
    1. Turn the ignition off.
    2. Remove the EGR Valve Assembly.
    3. Visually inspect the EGR Valve stem, disc and passages for signs of damage or excessive carbon build up.

      Does the EGR Valve show signs of excessive carbon or soot build up?

      Yes 

      • Clean and reinstall the EGR Valve Assembly. The EGR VALVE REPLACED routine must be performed after replacing or cleaning the EGR Valve to reset the zero learn position. Failure to do so will cause a false failure and the P1404 DTC to set. With the scan tool, perform the EGR VALVE REPLACED routine. Test drive the vehicle and verify the DTC does not return.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to: 3.6L - POWERTRAIN VERIFICATION TEST .

      No 

      • Replace the EGR Valve Assembly in accordance with the Service Information. Refer to: VALVE, EXHAUST GAS RECIRCULATION (EGR), REMOVAL AND INSTALLATION . The EGR VALVE REPLACED routine must be performed after replacing or cleaning the EGR Valve to reset the zero learn position. Failure to do so will cause a false failure and the P1404 DTC to set. With the scan tool, perform the EGR VALVE REPLACED routine.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to: 3.6L - POWERTRAIN VERIFICATION TEST .
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