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 FOR AN ACTIVE DTC
NOTE:
Check for contaminants that may have damaged the O2 Sensor: contaminated fuel, unapproved silicone, oil and coolant.
1. Start the engine.
2. Test drive the vehicle. Try to repeat the conditions in which the fault originally set by reviewing the Freeze Frame data, or in accordance with the When Monitored condition.
3. With the scan tool, read DTCs and record on the repair order.
  Is the DTC active or pending?
  
  Yes
  - Go To 2
  No
  - Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
CHECK THE EXHAUST SYSTEM FOR LEAKS
1. Perform the CHECKING THE EXHAUST SYSTEM FOR LEAKS test procedure. Refer to CHECKING THE EXHAUST SYSTEM FOR LEAKS .
  Were any exhaust leaks found?
  
  Yes
  - Repair or replace the leaking exhaust parts as necessary.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 3
CHECK THE (K141) O2 SENSOR 1/2 SIGNAL CIRCUIT
1. Turn the ignition off.
2. Disconnect the O2 Sensor 1/2 harness connector.
3. Turn the ignition on.
4. Measure the voltage on the (K141) O2 Sensor 1/2 Signal circuit in the O2 Sensor 1/2 harness connector.
  Is the voltage between 0.12 and 0.09 volts?
  
  Yes
  - Go To 4
  No
  - Check the O2 Sensor 1/2 Signal circuit for a short to ground, open or short to voltage. If OK, replace and program the PCM in accordance with the Service Information. Refer to MODULE, POWERTRAIN CONTROL, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK THE (K904) O2 SENSOR RETURN CIRCUIT
1. Measure the voltage on the (K904) O2 Sensor Return circuit at the O2 Sensor 1/2 harness connector.
  Is the voltage at 0.11 volts?
  
  Yes
  - Go To 5
  No
  - Check the (K904) O2 Sensor Return circuit for a short to ground, open or short to voltage. If OK, replace and program the PCM in accordance with the Service Information. Refer to MODULE, POWERTRAIN CONTROL, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
OXYGEN SENSOR
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. Perform any Service Bulletins that may apply.
  Were any problems found?
  
  Yes
  - Repair as necessary.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Replace the Oxygen Sensor 1/2 in accordance with the Service Information. Refer to SENSOR, OXYGEN, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .