Diagnostic Test

CHECK FOR AN ACTIVE CONDITION
1. With the scan tool, read Powertrain Control Module (PCM) DTCs and Freeze Frame Data and record on the repair order.
2. Using the recorded Freeze Frame Data and the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
3. With the scan tool, read PCM DTCs.
  Is the DTC active or pending?
  
  Yes
  - Go To 2
  No
  - Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
CHECK FOR OTHER DTCS
1. Refer to the recorded DTCs.
  Are there any other O2 Sensor Heater circuit DTCs active or pending?
  
  Yes
  - Perform the applicable diagnostic procedure(s). Refer to 2.0L - DIAGNOSTIC CODE INDEX .
  No
  - Go To 3

CHECK THE O2 SENSOR 1/1 HEATER ELEMENT RESISTANCE

Turn the ignition off.
NOTE:
Allow the O2 Sensor heater a few minutes to cool down from the heater test performed with the scan tool.
Disconnect the O2 Sensor 1/1 harness connector.

Measure the resistance of the O2 Sensor 1/1 Heater Element across the O2 Sensor, between the O2 Heater Control terminal and the Heater ground terminal (component side).

NOTE:

If possible, it's best to measure the O2 Sensor 1/1 Heater Element resistance value at approximately 20°C (68°F). The resistance value will vary with different temperature values. If the O2 Sensor is obviously warmer or cooler than the recommended temperature, use the table below to estimate what the resistance range should be. The MAXIMUM allowable resistance would be approximately 12.5 Ohms at 1000°C.

Celsius	Fahrenheit	Resistance Range
0°C	32°F	3.1 - 4.2 Ohms
20°C	68°F	3.3 - 4.4 Ohms
100°C	212°F	3.85 - 5.1 Ohms

Is the O2 Sensor resistance within the acceptable range?

Yes

Go To 4

Replace the O2 Sensor in accordance with the Service Information. Refer to SENSOR, OXYGEN, REMOVAL AND INSTALLATION .
Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

CHECK FOR HIGH RESISTANCE IN THE (Z909) O2 SENSOR GROUND CIRCUIT
1. Measure the resistance between ground and the (Z909) O2 Sensor Ground circuit at the O2 Sensor 1/1 harness connector.
  Is the resistance below 3.0 Ohms?
  
  Yes
  - Go To 5
  No
  - Repair the (Z909) O2 Sensor Ground circuit for an open circuit.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK FOR HIGH RESISTANCE IN THE (K79) O2 SENSOR 1/1 HEATER CONTROL CIRCUIT
1. Disconnect the PCM C2 harness connector.
2. Measure the resistance of the (K79) O2 Sensor 1/1 Heater Control circuit between the Oxygen Sensor 1/1 harness connector and the PCM C2 harness connector.
  Is the resistance below 3.0 Ohms?
  
  Yes
  - Go To 6
  No
  - Repair the (K79) O2 Sensor 1/1 Heater Control circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK RELATED PCM AND COMPONENT CONNECTIONS
1. Perform any Service Bulletins that apply.
2. Disconnect all PCM harness connectors.
3. Disconnect all related in-line harness connections (if equipped).
4. Disconnect the related component harness connectors.
5. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
  - Proper connector installation.
  - Damaged connector locks.
  - Corrosion.
  - Other signs of water intrusion.
  - Weather seal damage (if equipped).
  - Bent terminals.
  - Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
  - Terminals that have been pushed back into the connector cavity.
  - Check for spread terminals and verify proper terminal tension.
  Repair any conditions that are found.
6. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
7. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
9. With the scan tool, erase DTCs.
10. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
11. With the scan tool, read DTCs.
  Did the DTC return?
  
  Yes
  - Replace and program the Powertrain Control Module (PCM) in accordance with the Service information. Refer to MODULE, POWERTRAIN CONTROL (PCM), REMOVAL AND INSTALLATION .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  - Test complete.