Diagnostic Test

1) O2 SENSOR ABOVE 3.7 VOLTS

Fig 1: SCAN TOOL (STARSCAN)
Courtesy of DAIMLERCHRYSLER CORP.

NOTE: When only one O2 Sensor is shorted to voltage, the scan tool will display all O2 Sensor voltage readings at approximately 5.0 volts. When diagnosing this DTC, only diagnose the O2 Sensor that set the DTC.

Start the engine.

Allow the engine to reach normal operating temperature.

With a scan tool, read the 1/2 O2 Sensor voltage.

Is the voltage above 3.7 volts?

Yes
1. Go To step 2).
No
1. Refer to INTERMITTENT CONDITION .
2. Perform NGC POWERTRAIN VERIFICATION TEST VER - 5 .
2) (K141) O2 1/2 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE

Fig 2: Checking Left Rear O2 Sensor Signal Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Start the engine and allow the engine to idle.

Disconnect the 1/2 O2 Sensor harness connector.

Measure the voltage on the (K141) O2 Sensor 1/2 Signal circuit in the O2 Sensor harness connector.

NOTE: Measure the voltage in reference to ground, not the (K904) O2 Downstream Return circuit.

Is the voltage above 5.2 volts?

Yes
1. Repair the short to battery voltage in the (K141) O2 Sensor 1/2 Signal circuit.
2. Perform NGC POWERTRAIN VERIFICATION TEST VER - 5 .
No
1. Go To step 3).
3) (K904) O2 DOWNSTREAM RETURN CIRCUIT SHORTED TO BATTERY VOLTAGE

Fig 3: Checking Left Rear O2 Sensor Return Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the PCM harness connectors.

Ignition on, engine not running.

Measure the voltage on the (K904) O2 Downstream Return circuit in the O2 Sensor harness connector.

Is there any voltage present?

Yes
1. Repair the short to battery voltage in the (K904) O2 Downstream Return circuit.
2. Perform NGC POWERTRAIN VERIFICATION TEST VER - 5 .
No
1. Go To step 4).
4) O2 SENSOR

Fig 4: Checking Left Rear O2 Sensor Signal Circuit & Return Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Connect the PCM harness connectors.

Connect a jumper wire between the (K141) O2 1/2 Signal circuit and the (K904) O2 Downstream Return circuit in the 1/2 O2 Sensor harness connector.

Ignition on, engine not running.

With a scan tool, monitor the 1/2 O2 Sensor voltage.

Is the voltage between 2.3 and 2.7 volts with the jumper wire installed?

Yes
1. Replace the O2 Sensor.
2. Perform NGC POWERTRAIN VERIFICATION TEST VER - 5 .
No
1. Go To step 5).
  NOTE: Remove the jumper wire before continuing.
5) (K141) O2 1/2 SIGNAL CIRCUIT OPEN

Fig 5: Checking Left Rear O2 Sensor Signal Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

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 Miller Special Tool #8815 to perform diagnosis.

Measure the resistance of the (K141) O2 1/2 Signal circuit from the O2 Sensor harness connector to the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?

Yes
1. Go To step 6).
No
1. Repair the open in the (K141) O2 1/2 Signal circuit.
2. Perform NGC POWERTRAIN VERIFICATION TEST VER - 5 .
6) (K904) O2 DOWNSTREAM RETURN CIRCUIT OPEN

Fig 6: Checking Left Rear O2 Sensor Return Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Measure the resistance of the (K904) O2 Downstream Return circuit from the O2 Sensor harness connector to the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?

Yes
1. Go To step 7).
No
1. Repair the open in the (K904) O2 Downstream Return circuit.
2. Perform NGC POWERTRAIN VERIFICATION TEST VER - 5 .
7) PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

Were there any problems found?

Yes
1. Repair as necessary.
2. Perform NGC POWERTRAIN VERIFICATION TEST VER - 5 .
No
1. Replace and program the Powertrain Control Module. Refer to MODULE-POWERTRAIN CONTROL .
2. Perform NGC POWERTRAIN VERIFICATION TEST VER - 5 .