Diagnostic Test

WARNING: This page is about a different car, the 2016 Jeep Wrangler and 2015 Jeep Wrangler. However, it is still accessible from the selected car via links, so may be relevant.

ACTIVE DIAGNOSTIC TROUBLE CODE (DTC)
NOTE:
A new rear O2 Sensor along with an aging front O2 Sensor may cause the DTC to set. Review the repair history of the vehicle before continuing.

NOTE:
If an O2 Sensor DTC set along with the Catalytic Converter Efficiency DTC diagnose the O2 Sensor DTCs before continuing.

NOTE:
Check for contaminants that may have damaged the O2 Sensor and Catalytic Converter: contaminated fuel, unapproved silicone, oil and coolant, repair necessary.
1. Start the engine.
2. Allow the engine to reach normal operating temperature.
3. With the scan tool, read DTCs.
  NOTE:
  It may be necessary to drive the vehicle to meet the conditions to set this DTC, try to repeat the conditions in which the fault originally set by reviewing the Freeze Frame data.
  
  Is the DTC Active or Pending at this time?
  
  Yes
  - Go To 2
  No
  - Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
VISUALLY INSPECT CATALYTIC CONVERTER
1. Inspect the Catalytic Converter for the following damage:
  - Damage Catalytic Converter, dents or holes.
  - Severe discoloration caused by overheating the Catalytic Converter.
  - Catalytic Converter broke internally.
  - Inspect both ends of the converter, inlet and outlet.
  - Leaking Catalytic Converter.
  Were any problems found?
  
  Yes
  - Replace the Catalytic Converter. Repair the condition that may have caused the failure. Refer to CONVERTER, CATALYTIC, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 3
(K902) O2 SENSOR 1/1 RETURN CIRCUIT VOLTAGE CHECK

Fig 1: Checking O2 Sensor Return Circuit Voltage
Courtesy of CHRYSLER GROUP, LLC
1. Turn the ignition off.
2. Disconnect the O2 Sensor 1/1 harness connector.
3. Turn the ignition on.
4. Measure the voltage on the (K902) O2 Sensor 1/1 Return circuit in the O2 Sensor 1/1 harness connector.
  Is the voltage at 2.5 Volts?
  
  Yes
  - Go To 4
  No
  - Go To 5
(K904) O2 SENSOR 1/2 RETURN CIRCUIT VOLTAGE CHECK

Fig 2: Checking O2 Sensor Return Circuit Voltage
Courtesy of CHRYSLER GROUP, LLC
1. Turn the ignition off.
2. Disconnect the O2 Sensor 1/2 harness connector.
3. Turn the ignition on.
4. Measure the voltage on the (K904) O2 Sensor 1/2 Return circuit in the O2 Sensor 1/2 harness connector.
  Is the voltage at 2.5 Volts?
  
  Yes
  - Go To 10
  No
  - Go To 7
(K902) O2 SENSOR 1/1 RETURN CIRCUIT SHORTED TO GROUND

Fig 3: Checking O2 Sensor Return Circuit For Short To Ground
Courtesy of CHRYSLER GROUP, LLC
1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
3. Measure the resistance between ground and the (K902) O2 Sensor 1/1 Return circuit in the O2 Sensor 1/1 harness connector.
  Is the resistance below 100 ohms?
  
  Yes
  - Repair the short to ground in the (K902) O2 Sensor 1/1 Return circuit.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 6
(K902) O2 SENSOR 1/1 RETURN CIRCUIT OPEN

Fig 4: Checking O2 Sensor Signal Circuit For Open Or High Resistance
Courtesy of CHRYSLER GROUP, LLC
1. Measure the resistance of the (K902) O2 Sensor 1/1 Return circuit from the O2 Sensor 1/1 harness connector to the PCM C2 harness connector.
  Is the resistance below 5.0 ohms?
  
  Yes
  - Go To 9
  No
  - Repair the open in the (K902) O2 Return Upstream circuit.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
(K904) O2 SENSOR 1/2 RETURN CIRCUIT SHORTED TO GROUND

Fig 5: Checking O2 Sensor Return Circuit For Short To Ground
Courtesy of CHRYSLER GROUP, LLC
1. Turn the ignition off.
2. Disconnect the O2 Sensor 1/2 harness connector.
3. Measure the resistance between ground and the (K904) O2 Sensor 1/2 Return circuit in the O2 Sensor 1/2 harness connector.
  Is the resistance below 100 ohms?
  
  Yes
  - Repair the short to ground in the (K904) O2 Sensor 1/2 Return circuit.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 8
(K904) O2 SENSOR 1/2 RETURN CIRCUIT OPEN

Fig 6: Checking O2 Sensor Return Circuit For Open
Courtesy of CHRYSLER GROUP, LLC
1. Measure the resistance of the (K904) O2 Sensor 1/2 Return circuit from the O2 Sensor 1/2 harness connector to the PCM C2 harness connector.
  Is the resistance below 5.0 ohms?
  
  Yes
  - Go To 9
  No
  - Repair the open in the (K904) O2 Sensor 1/2 Return circuit.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Sensor and the Powertrain Control Module (PCM).
  - Look for any chafed, pierced, pinched or partially broken wires.
  - Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Sensor and the Powertrain Control Module connectors.
  - Perform any Technical Service Bulletins that may apply.
  Were there any problems found?
  
  Yes
  - Repair as necessary.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Replace and program the Powertrain Control Module in accordance with the Service Information. Refer to MODULE, POWERTRAIN CONTROL, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

CHECKING THE EXHAUST SYSTEM FOR LEAKS

Turn the ignition off.
Raise the vehicle in accordance with the Service Information.
WARNING:
The normal operating temperature of the exhaust system is very high. Never work around or attempt to service any part of the exhaust system until it has cooled. Special care should be taken when working near the catalytic converter. The temperature of the converter rises to a high level after a short period of engine operating time.
Connect (special tool #8404-EC, Exhaust Cone) or (special tool #8404-EC, Exhaust Cone) to Air Pressure Regulator (with hose) W-18-MIL-1146AS.
CAUTION:
The air pressure must not exceed 27.6 kPa (4 psi), otherwise engine damage can occur.
Attach shop air to the air pressure regulator.
Adjust the Air Pressure Regulator to 27.6 kPa (4 psi).
Insert the exhaust cone into the vehicle tail pipe.
If the vehicle is equipped with dual exhaust. Use the (special tool #8404-ECT, Exhaust Cone, Truck) with equipped attached plug, plug one side of the dual exhaust pipe. Pressurize the other as described above.
Apply Mopar® Air Leak Detector PN# 05191804AA (or an equivalent leak finder liquid) to the following areas:
- All welded joints from the exhaust manifold to 152.4 mm (6 inches) behind the downstream O2 Sensor
- O2 Sensor seal points
- O2 Sensor boss welds
- Flange/joint connection(s)
- Exhaust manifold to cylinder head connection(s)
- EGR solenoid gasket base and tube seal points (if equipped)
Watch for the liquid/soapy water to bubble.

Use the following definitions to help determine if system or component repair/replacement is necessary:

Type 1 Leak is defined as a leak where very small foam like bubbles 1.0 mm (0.04 inch) or less appear. Any Type 1 or greater leaks found in welded joints, O2 Sensor seal points or O2 Sensor boss welds must be repaired or the component must be replaced.
Type 2 Leak is defined as a leak where larger bubbles pea size, 8.0 mm (0.3 inch) or greater appear. Any Type 2 or greater leaks found in flange or joint connections, exhaust manifold to cylinder head connections or EGR gasket and tube seal points must be repaired or the components must be replaced.

Leak Location	Repair required if results at 4 psi reveal bubble size:
Welded joints	Type 1, 1 mm (0.04 inch) or greater
O2 Sensor seal points	Type 1, 1 mm (0.04 inch) or greater
O2 Sensor boss welds	Type 1, 1 mm (0.04 inch) or greater
Flange / joint connections	Type 2, 8 mm (0.3 inch) or greater
Exhaust Manifold to cylinder head connections	Type 2, 8 mm (0.3 inch) or greater
EGR gasket and tube seal points	Type 2, 8 mm (0.3 inch) or greater

If a leak is found that matches the above definition, repair or replace the component as necessary.
Once the repair is complete, repeat the procedure to verify that all leaks have been repaired.
Were any exhaust leaks found?

Yes
- Repair or replace the leaking exhaust parts as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 11

ENGINE MECHANICAL CONDITION
1. Check the exhaust for excessive smoke caused by an internal problem in the engine.
  Is an engine mechanical condition present?
  
  Yes
  - Repair the engine mechanical condition as necessary.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 12
AGING O2 SENSOR
1. A new Downstream O2 Sensor along with an aging Upstream O2 Sensor may cause the DTC to set.
2. Review the vehicles repair history.
  Has the Downstream O2 Sensor been replaced without replacing the Upstream O2 Sensor?
  
  Yes
  - Replace the front O2 Sensor as necessary. Refer to SENSOR, OXYGEN, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 13
CATALYTIC CONVERTER
If there are no possible cause remaining, view repair.

Repair
- Replace the Catalytic Converter. Refer to CONVERTER, CATALYTIC, REMOVAL .
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .