Mar 102019

Chevy Impala

2 days ago a light on dash flashed Change Engine Oil. When light came on engine developed a severe misfire and lifters started chattering. What is the most likely cause(s),and how much is repair most likely to cost.

Difficult to say without looking at it. Check the engine oil level. If there is no oil detected you may add oil to see if the chattering decreases. Until the issue is narrowed down it would be premature to put a price tag on it.

Understanding an Engine Misfire

Engine Oil Light, Diagnosis & Testing

  1. Understand and validate customer concern. Inspect visible system components for obvious damage or conditions that may cause concern.
  2. Inspect for related bulletins, recall/field actions and preliminary information.
  3. Verify symptom is not exclusively a mechanical concern.
  4. Connect a suitably programmed scan tool, perform vehicle DTC Information function and verify at least one control module communicates with scan tool.
  5. Verify there are no control module Internal hardware performance DTCs set.
  6. Ignition ON, command MIL ON and OFF with scan tool. MIL should turn ON and OFF as commanded.
  7. Ignition ON, command MIL ON and OFF with a scan tool while observing following control circuit status parameters:
    • a. MIL control circuit low voltage test status.
    • b. MIL control circuit open test status.
    • c. MIL control circuit high voltage test status.
    • d. Each parameter should toggle between OK and Not Run or Not Run and OK.
  8. Ignition OFF, disconnect MIL electrical harness connectors. Ignition ON, MIL should not illuminate. If MIL is illuminated, test MIL control circuit terminal for a short to ground. If circuit tests normal, replace cluster.
  9. Ignition ON, connect a 3A fused jumper wire between MIL control circuit terminal and ground. MIL should illuminate. If MIL does not illuminate, test MIL control circuit for a short to voltage, or an open/high resistance. If circuit tests normal, replace MIL bulb.
  10. If all circuits/connections test normal, replace ECM.

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