Diagnostic Test

ACTIVE DTC
1. Ignition on, engine not running.
2. With a scan tool, read DTC's.
Q: Is the DTC active at this time?

Yes :
- Go To 2
No :
- Refer to the INTERMITTENT CONDITION Diagnostic Procedure .
- Perform the POWERTRAIN VERIFICATION TEST .
O2 HEATER ELEMENT
1. Turn the ignition off.
  NOTE: Allow the O2 Sensor to cool down to room temperature.
2. Disconnect the 2/2 O2 Sensor harness connector.
3. Measure the resistance across the O2 Sensor Heater element, between the O2 Heater Control terminal and the O2 Heater ground terminal in the component connector.
  NOTE: O2 Heater Element resistance values should be measured at 70°F (21.1°C). The resistance value will vary with different temperature values.
Q: Is the O2 Sensor Heater Element resistance between 2.0 and 30.0 ohms?

Yes :
- Go To 3
No :
- Replace the O2 Sensor.
- Perform the POWERTRAIN VERIFICATION TEST .
(K399) O2 2/2 HEATER CONTROL CIRCUIT

Fig 1: Identifying Heated Oxygen Sensor Connector Terminals
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
1. Ignition on, engine not running.
2. With a scan tool, actuate the O2 2/2 Heater Test with the Sensor harness connector still disconnected.
3. Using a 12-volt test light connected to ground, probe the (K399) O2 2/2 Heater Control circuit in the O2 Sensor harness connector.
Q: Does the test light illuminate brightly and flash on and off during the actuation?

Yes :
- Go To 4
No :
- Go To 5
(Z992) O2 HEATER GROUND CIRCUIT OPEN

Fig 2: Identifying O2 Sensor Connector Terminals
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
1. Turn the ignition off.
2. Measure the resistance between an engine ground and the (Z992) O2 2/2 Heater ground circuit in the O2 Sensor harness connector.
Q: Is the resistance below 5.0 ohms?

Yes :
- Replace the O2 Sensor.
- Perform the POWERTRAIN VERIFICATION TEST .
No :
- Repair the open in the (Z992) O2 2/2 Heater ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST .
(K399) O2 2/2 HEATER CONTROL CIRCUIT SHORTED TO BATTERY VOLTAGE

Fig 3: Identifying Heated Oxygen Sensor Connector Terminals
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
1. Turn the ignition off.
2. Disconnect the C3 PCM harness connector.
3. Ignition on, engine not running.
4. Using a 12-volt test light connected to ground, probe the (K399) O2 Heater 2/2 Control circuit in the O2 Sensor harness connector.
Q: Does the test light illuminate?

Yes :
- Repair the short to battery voltage in the (K399) O2 2/2 Heater Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST .
No :
- Go To 6
(K399) O2 2/2 HEATER CONTROL CIRCUIT OPEN

Fig 4: Checking O2 2/2 Heater Control Circuit Open
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
1. 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.
2. Measure the resistance of the (K399) O2 2/2 Heater Control circuit from the O2 Sensor harness connector to the appropriate terminal of special tool #8815.
Q: Is the resistance below 5.0 ohms?

Yes :
- Go To 7
No :
- Repair the open in the (K399) O2 2/2 Heater Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST .
PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
1. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Q: Were there any problems found?

Yes :
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST .
No :
- Replace and program the Powertrain Control Module per Service Information.
- Perform the POWERTRAIN VERIFICATION TEST .