Diagnostic Test

WARNING: This page is about a different car, the 2024 Jeep Grand Wagoneer L and 2024 Jeep Grand Wagoneer. However, it is still accessible from the selected car via links, so may be relevant.

READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR THE 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 2
  No
  - Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
CHECK FOR AN INTAKE MANIFOLD LEAK AT CYLINDER 4
1. Check for any of the following conditions, but not limited to:
  - Intake manifold seals leaking cylinder 4.
  - Intake plenum leak at cylinder 4.
  - Warped/cracked Intake Manifold or plenum.
  - Vacuum leak at the Fuel Injector O-Ring.
  Were any issues found?
  
  Yes
  - Perform the appropriate repairs.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 3
CHECK FOR FUEL INJECTOR ISSUES AT CYLINDER 4
1. Check for any of the following conditions, but not limited to:
  - Verify correct voltage supply at the Fuel Injector.
  - Verify correct control circuit operation at the Fuel Injector.
  - Verify correct Fuel Injector operation (spray pattern).
  Were any issues found?
  
  Yes
  - Repair as necessary.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 4
CHECK CYLINDER 4 FOR LOW COMPRESSION AND IGNITION SYSTEM ISSUES
1. Perform a cylinder compression and/or cylinder leak down test on cylinder 4.
2. Check the ignition system for any of the following conditions, but not limited to:
  - Verify correct voltage supply at the Ignition Coil.
  - Verify correct control circuit operation at the Ignition Coil.
  - Verify that the Spark Plug is equivalent to OEM specifications.
  - Verify correct Spark Plug gap.
  - Visually inspect the Ignition Coil and Spark Plug for signs of carbon tracking.
  - Visually inspect the Ignition Coil for signs of damage.
  Were any issues found?
  
  Yes
  - Repair as necessary.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 5
CLEAN THE VALVE TRAIN AND COMBUSTION CHAMBERS
1. Using the Mopar Combustion cleaner, de-carbon the engine.
2. After driving and clearing the combustion cleaner from the engine, erase any DTCs with the scan tool.
3. Test drive the vehicle in accordance with the when monitored conditions.
4. With the scan tool, read DTCs.
  Is the DTC active or pending?
  
  Yes
  - Go To 6
  No
  - Repair is complete.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK FOR VALVETRAIN SYSTEM ISSUES
1. Check the valvetrain for any of the following conditions, but not limited to:
  - Check for broken, worn or improperly installed valve springs.
  - Check for broken, worn or improperly installed Camshaft followers.
  - Check for worn Camshaft lobes.
  Were any issues found?
  
  Yes
  - Repair as necessary.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 7
O2 SENSOR
1. Replace the Bank 2 Upstream O2 Sensor.
2. With the scan tool, erase DTCs.
3. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
4. With the scan tool, read DTCs.
  Did the DTC return?
  
  Yes
  - Anything that can cause an air/fuel ratio imbalance in an individual cylinder will cause this DTC to set. Verify all of the items in this test and any other mechanical items that may cause this DTC to set. Also check for any Service Bulletins that may apply to this fault code.
  No
  - Repair is complete.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .