P0343

DTC P0343

Circuit Description

The camshaft position (CMP) sensor works in conjunction with a 1 X reluctor wheel on the camshaft. The powertrain control module (PCM) provides a 12-volt reference to the CMP sensor as well as a low reference and a signal circuit.

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 CMP sensor lx signal is used by the PCM to determine if the cylinder at top dead center (TDC) is on the firing stroke or the exhaust stroke. The PCM can determine TDC for all cylinders by using the CKP sensor signal alone. The engine will stand without a CMP signal as long as the PCM receives the CKP sensor signal. A slightly longer cranking time may be a symptom of this condition. The system attempts synchronization and looks for an increase in engine speed indicating that the engine started. If the PCM does not detect an increase in engine speed, the PCM assumes that the PCM incorrectly synchronized to the exhaust stroke and re-syncs to the opposite cam position. If the PCM detects that the CMP signal is constantly high, this DTC sets.


DTC Descriptors

This diagnostic procedure supports the following DTC. DTC P0342 Camshaft Position (CMP) Sensor Circuit High Frequency


Conditions for Running the DTC

- The engine is operating.

- The engine speed is more than 400 RPM.

- DTC P0343 runs continuously once the above conditions are met.

Conditions for Setting the DTC

The PCM detects that the CMP sensor signal is high for 1.5 seconds.

Action Taken When the DTC Sets

- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

- Clear the MIL and the DTC with a scan tool.


Diagnostic Aids

- The following conditions may cause this DTC to set:

- Camshaft reluctor ring damage

- The sensor coming in contact with the reluctor ring

- Foreign material passing between the sensor and the reluctor ring

- Excessive camshaft end-play

- Wiring routed too close to secondary ignition components

- If the condition is intermittent, refer to Intermittent Conditions.Symptom Related Diagnostic Procedures


Test Description

DTC P0343 Steps 1-6:

DTC P0343 Steps 7-16:

The number below refers to the step number on the diagnostic table.

4. This step tests the CMP sensor and circuits from the CMP sensor to the PCM. If there is not duty cycle displayed or if the duty cycle is not within range there is a problem with the sensor or the circuits.