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Home >> Fiat >> 2016 >> 500 Turbo, Standard Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 120 (1.4L 16-Valve - DTCS P0016-00 To P0353-00 - 500) >> DTC Troubleshooting >> P0300-00-Multiple Cylinder Misfire >> Diagnostic Test

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.
  1. CHECK FOR AN ACTIVE DTC 
    1. Diagnose and repair any other active component or circuit DTCs before continuing with this procedure.
    2. Turn the ignition on.
    3. With the scan tool, read DTCs. Copy DTC and Freeze Frame information.
      NOTE:

      Attempt to operate the vehicle under conditions similar to which the DTC was set.

      NOTE:

      It may be necessary to test drive the vehicle within the DTC monitoring conditions in order for this DTC to set.

    4. With the scan tool, read DTCs.

      Is the DTC active or pending?

      Yes 

      • Go To  2

      No 

  2. DIAGNOSTIC INSPECTION 
    NOTE:

    Anything that affects the speed of the crankshaft can cause this DTC to set.

    NOTE:

    When a misfire is detected, the PCM will shut down the injector control circuit for the misfiring cylinder.

    NOTE:

    Misfire may occur and may not be caused by component failure. Any of the following conditions can cause a misfire:

    • Worn serpentine belt.
    • Misalignment or binding generator or A/C compressor pulleys.
    • Improper CKP, CMP, MAP, or TPS mounting.
    • Poor connector/terminal to component connection for CKP sensor, CMP sensor, MAP sensor, TPS, fuel injector, ignition coil, etc.
    • Corroded PCM power or ground circuits.
    • Intake manifold vacuum leaks.
    • Restriction in the air induction or exhaust system.
    • Internal engine component malfunction.
    • Moisture on ignition system components.
    • Insufficient fuel.
    • Low quality fuel.
    • Overfilled engine oil or transmission.
    • Extremely out of balance tires or warped brake rotors.
    • Manual transmission bog.
    • Towing overload.

    Were any problems found?

    Yes 

    • Repair as necessary in accordance with the Service Information.
    • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

    No 

    • Go To  3
  3. CHECKING THE FUEL DELIVERY SYSTEM 
    1. Perform the diagnostic procedures for CHECKING THE FUEL DELIVERY SYSTEM. Refer to CHECKING THE FUEL DELIVERY SYSTEM (HARD START) .

      Were any problems found?

      Yes 

      • Repair as necessary in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  4
  4. CHECKING THE IGNITION COIL OPERATION 
    1. Perform the diagnostic procedure for CHECKING THE IGNITION COIL OPERATION. Refer to CHECKING THE IGNITION COIL OPERATION .

      Were any problems found?

      Yes 

      • Repair as necessary in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  5
  5. ECT SENSOR OPERATION 
    NOTE:

    For this test to be valid, the thermostat must be operating correctly.

    NOTE:

    This test works best if performed on a cold engine (cold soak).

    1. Turn the ignition on.
    2. With the scan tool, read the Engine Coolant Temperature (ECT) Sensor value. If the engine was allowed to sit overnight (cold soak), the temperature value should be a sensible value that is somewhere close to the ambient temperature.
      NOTE:

      If engine coolant temperature is above 82°C (180°F), allow the engine to cool until 65°C (150°F) is reached.

    3. Start the Engine.
    4. During engine warm-up, monitor the ECT Sensor value. The temperature value change should be a smooth transition from start up to normal operating temperature 82° C (180° F). The value should reach at least 82° C (180° F).

      Did the ECT value increase smoothly and did it reach at least 82°C (180°F)?

      Yes 

      • Go To  6

      No 

  6. CHECKING THE MAP SENSOR OPERATION 
    1. Perform the diagnostic procedure for CHECKING THE MAP SENSOR OPERATION. Refer to CHECKING THE MAP SENSOR OPERATION .

      Were any problems found?

      Yes 

      • Repair as necessary in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  7
  7. CHECKING THE OXYGEN SENSOR OPERATION 
    1. Perform the diagnostic procedure for CHECKING THE OXYGEN SENSOR OPERATION. Refer to DIAGNOSIS AND TESTING .

      Were any problems found?

      Yes 

      • Repair as necessary in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  8
  8. CHECKING THE ENGINE MECHANICAL SYSTEM 
    1. Perform the diagnostic procedure for CHECKING THE ENGINE MECHANICAL SYSTEM. Refer to CHECKING THE ENGINE MECHANICAL SYSTEM .

      Were any problems found?

      Yes 

      • Repair as necessary in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  9
  9. 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 

      No 

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