Diagnostic Test

WARNING: This page is about a different car, the 2015 Fiat 500. However, it is still accessible from the selected car via links, so may be relevant.

CHECK THE O2 SENSOR HEATER ELEMENT
1. Turn the ignition off.
  NOTE:
  Allow the O2 Sensor to cool down to room temperature.
2. Disconnect the O2 Sensor 1/2 harness connector.
3. Measure the resistance of the O2 Sensor Heater Element across the O2 Sensor connector (component side) between the (K299) O2 Sensor Heater Control terminal and the (F344) Fused ASD Relay Output terminal.
  NOTE:
  The O2 Sensor Heater Element resistance values should be measured at approximately shop temperature. The resistance value can vary with if the O2 Sensor is extremely hot or cold. It is also important to zero your meter before taking this measurement.
  
  Is the resistance of the O2 Sensor Heater Element between 5.0 and 8.0 Ohms?
  
  Yes
  - Go To 2
  No
  - Verify that there is good pin to terminal contact in the O2 Sensor 1/2 and Powertrain Control Module connectors. If no problems are found, replace the O2 Sensor. Refer to SENSOR, OXYGEN, REMOVAL . When a new sensor is installed, a self-learn procedure should be completed. To do this, start the vehicle and allow it to idle for 30 seconds. Next, turn off the engine and let vehicle sit for 6 hours minimum where the temperature is between 0°C and 50°C (32°F and 122°F) ambient temperature. After the vehicle has sat, turn the key to the "Run" position for 10 seconds - DO NOT CRANK THE ENGINE. The learn is now complete and the vehicle can be started.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 16V Turbo .
CHECK FOR AN ACTIVE DTC
1. Turn the ignition off.
2. Reconnect the O2 Sensor 1/2 harness connector.
  NOTE:
  Wait a minimum of eight minutes to allow the O2 Sensor to cool down before continuing the test.
3. Start the engine and allow it to run for at least five minutes.
4. With the scan tool, read DTCs and record on the repair order.
  Is the DTC active or pending?
  
  Yes
  - Go To 3
  No
  - Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
CHECK THE (K299) O2 SENSOR 1/2 HEATER CONTROL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Turn the ignition off.
2. Disconnect the O2 Sensor 1/2 harness connector.
3. Disconnect the PCM C1 harness connector.
4. Check for continuity of the (K299) O2 Sensor 1/2 Heater Control circuit between the O2 Sensor 1/2 harness connector and the PCM C1 harness connector.
  Is the resistance below 0.5 Ohms?
  
  Yes
  - Go To 4
  No
  - Repair the excessive resistance in the O2 1/2 Heater Control circuit.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 16V Turbo .
CHECK THE (F344) FUSED ASD RELAY OUTPUT CIRCUIT FOR AN OPEN
1. Remove the ASD Relay.
2. Measure the resistance of the (F344) Fused ASD Relay Output circuit between the ASD Relay Output terminal and the O2 Sensor 1/2 harness connector.
  Is the resistance below 0.5 Ohms?
  
  Yes
  - Go To 5
  No
  - Repair the (F344) Fused ASD Relay Output circuit for an open circuit or short to ground.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 16V Turbo .
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 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, 16V Turbo .
  No
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 16V Turbo .
  - Test complete.