The Camshaft Position sensor is mounted through the top of the engine block at the rear of the valley cover. The CMP sensor works in conjunction with a 1X reluctor wheel on the camshaft. The reluctor wheel is inside the engine immediately in front of the rear cam bearing. The PCM provides a 12 volt power supply to the CMP sensor as well as a ground and a signal circuit.

The CMP sensor determines whether a cylinder is on a firing stroke or on an exhaust stroke. As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor. The sensors internal circuitry detects this and produces a signal which the PCM reads. The PCM uses this 1X signal in combination with the Crankshaft Position sensor 24X signal in order to determine crankshaft position and stroke. This diagnostic for the Camshaft Position sensor checks for a loss of Camshaft Position sensor signal.

Observe that as long as the 24X signal is available, the engine starts even if there is no Camshaft Position sensor signal. The PCM can determine when a particular cylinder is on either a firing or exhaust stroke by the 24X signal alone, but the PCM requires the cam signal in order to determine which (firing or exhaust). The system attempts synchronization and looks for an increase in MAF signal indicating the engine started. If the PCM does not detect a MAF increase, the PCM assumes it incorrectly synchronized to the exhaust stroke and re-syncs to the opposite cam position. A slightly longer cranking time may be a symptom of this condition.

The PCM detects that a CMP to CKP mis-match has occurred for 10 second.

A poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation may cause an intermittent.

Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked for the following conditions:

Refer to Symptoms .

Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If the DTC cannot be duplicated, the information included in the Freeze Frame and/or Failure Records data can be useful in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that were noted. This will isolate when the DTC failed.

The numbers below refer to the step numbers on the diagnostic table.

2. This step verifies that the malfunction is present.

3. This step checks for EMI (Electro Magnetic Interference) on the CMP sensor circuits.

6. Vertical lines across the face of the sensor could indicate foreign material passing between the CMP sensor and the reluctor wheel. This condition would cause this DTC to set.

7. Damage to the reluctor wheel would affect the CMP sensor output. If this condition exists, refer to Engine/Engine Mechanical for Camshaft replacement.