P0140
P0140-O2 SENSOR 1/2 SIGNAL INACTIVE
For a complete wiring diagram refer to the Wiring Information Electrical Diagrams.
- When Monitored:
For six minutes after engine start up and the vehicle speed between 20 and 55 MPH.
- Set Condition:
The O2 signal voltage does not switch lean or rich during monitoring for at least 2 to 4 minutes. Two Trip Fault. Three good trips to turn off the MIL.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
1. EXHAUST LEAK
NOTE: A thorough exhaust leak test must be completed before removing an O2 Sensor or any other part from the exhaust system. Do not remove any parts before an exhaust leak check has been completed.
NOTE: An exhaust leak may cause downstream fuel adaptives to rail out, resulting in a false 1/1 O2 Sensor failure.
1. Turn the ignition off.
2. Inspect the exhaust system for leaks between the engine and the 1/1 Oxygen Sensor.
3. Perform a leak test with Miller Tool #8404A Evaporative Emissions Leak Detector (EELD), even if an audible leak is not heard. Pay particular attention to the exhaust manifold to head surface, exhaust pipe to manifold connection, and the O2 sensor boss for leaks.
4. Connect the SMOKE supply tip (black hose) to the exhaust cone adapter (if equipped) and place it into the tail pipe.
5. Set the smoke/air control switch to SMOKE.
6. Press the remote smoke/air start button.
7. While still holding the remote smoke/air start button, use the white light (#8404-CLL) to follow the exhaust system path and look for a leak, indicated by exiting smoke.
8. If a leak is concealed from view, release the remote smoke/air start button and use the ultraviolet (UV) black light #8404-UVL and the yellow goggles 8404-20 to look for residual traces of dye that is left behind by the smoke.
9. The exiting smoke deposits a residual fluid that is either bright green or bright yellow in color when viewed with a UV light.
Were any exhaust leaks found?
Yes
- Repair as necessary.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 2
2. DTC IS ACTIVE
NOTE: Check for contaminants that may have damaged the O2 Sensor: contaminated fuel, unapproved silicone, oil and coolant.
NOTE: It may be necessary to test drive the vehicle within the DTC monitoring conditions in order for this DTC to set.
1. Start the engine and allow it to reach operating temperature.
WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.
2. With a scan tool, select View DTCs.
Is the status Active for this DTC?
Yes
- Go To 3
No
- Refer to the CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. Checking for an Intermittent DTC.
3. (K141) O2 1/2 SIGNAL CIRCUIT SHORTED TO VOLTAGE
1. Start the engine and allow it to idle.
2. Disconnect the Oxygen Sensor 1/2 harness connector.
3. Measure the voltage on the (K141) O2 1/2 Signal circuit in the Oxygen Sensor 1/2 harness connector.
NOTE: Measure the voltage in reference to ground, not the (K904) O2 1/2 Return circuit.
Is the voltage above 5.2 volts?
Yes
- Repair the (K141) O2 1/2 Signal circuit for a short to voltage.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 4
4. (K904) O2 1/2 RETURN CIRCUIT SHORTED TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the Powertrain Control Module (PCM) harness connector.
3. Turn the ignition on.
4. Measure the voltage on the (K904) O2 1/2 Return circuit in the Oxygen Sensor 1/2 harness connector.
Is there any voltage present?
Yes
- Repair the (K904) O2 1/2 Return circuit for a short to voltage.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 5
5. (K141) O2 1/2 SIGNAL CIRCUIT SHORTED TO GROUND
1. Turn the ignition off.
2. Measure the resistance between ground and the (K141) O2 1/2 Signal circuit in the Oxygen Sensor 1/2 harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the (K141) O2 1/2 Signal circuit for a short to ground.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 6
6. (K904) O2 1/2 RETURN CIRCUIT SHORTED TO GROUND
1. Measure the resistance between ground and the (K904) O2 1/2 Return circuit in the Oxygen Sensor 1/2 harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the (K904) O2 1/2 Return circuit for a short to ground.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 7
7. (K141) O2 1/2 SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE
1. Measure the resistance of the (K141) O2 1/2 Signal circuit between the Oxygen Sensor 1/2 harness connector to the Powertrain Control Module (PCM) harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go To 8
No
- Repair the (K141) O2 1/2 Signal circuit for an open circuit or high resistance.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
8. (K904) O2 1/2 RETURN CIRCUIT OPEN OR HIGH RESISTANCE
1. Measure the resistance of the (K904) O2 1/2 Return circuit between the Oxygen Sensor 1/2 harness connector to the Powertrain Control Module (PCM) harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go To 9
No
- Repair the (K904) O2 1/2 Return circuit for an open circuit or high resistance.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
9. OXYGEN SENSOR 1/2
NOTE: Prior to replacing the O2 sensor, verify that the correct part number is being used in order to prevent improper O2 heater control.
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Oxygen Sensor 1/2 and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Search for any Technical Service Bulletins (TSBs) that may apply.
Were any problems found?
Yes
- Repair as necessary.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Replace the Oxygen Sensor 1/2.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.