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Owners of a 2012-2014 Chevy Sonic may complain about an intermittent engine no-crank. They may note that if they cycle the ignition off and then back on, the engine may crank.

The condition may be caused by the ECM receiving an intermittent exhaust camshaft position sensor (CMP) signal as soon as the ignition is turned on. This results in the ECM not sending a crank request signal because it has determined that the engine is already running.

NOTE: Do not replace the exhaust CMP sensor based solely on the description of this condition.

1. Connect a scan tool.

2. Turn the ignition on (engine off).

3. Perform a diagnostic system check. Record any stored DTCs.

With the ignition on and engine off, observe one of the following active counter parameters for incrementing:

  • Exhaust CMP active counter, or
  • Exhaust camshaft position active counter.

If the active counter parameter is incrementing, replace the exhaust CMP sensor.

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