Trouble CodesGM OBD Trouble CodesGM Code 41

CODE 41 - No Distributor Pulses, Cylinder Select Error

Trouble Code 41 indicates that the Camshaft Sensor is not functioning properly.

The ignition module uses the Cam Sensor signal for timing the spark firing. The ignition module also passes this signal to the ECM to enable sequential fuel injection. The inability to properly determine engine position from the Cam Sensor will generate Code 41.

The engine will continue to run if the signal is lost from the sensor, however it will not restart after shut down. If the Cam signal from the ignition module to the ECM is lost while running, the ECM will switch to the simultaneous fuel injection mode. The engine can be re-started but will continue to run in the simultaneous mode as long as the fault is present.

The conditions for setting this code are:

  • the engine is running, and
  • the Cam Sensor signal is not received by the ECM in the last 1 second interval

Typical causes for this code include:

1) Loose or mis-adjusted Cam Sensor
2) Defective Cam Sensor-to-ECM connections
3) Defective ECM

Cam sensor installation and adjustment procedures call for very exact tolerances. It is for this reason that it is recommended that the service manual be consulted while performing any adjustment or replacement of the Camshaft Sensor.

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