Case IH 3955 – ENGINE: Intake Camshaft Position (CMP) Sensor Performance Bank 1 / Camshaft Sensor Error - Invalid Signal

The Engine Control Module (ECM) is receiving an invalid, erratic, or out-of-range signal from the camshaft position sensor, indicating a potential loss of synchronization between the camshaft and crankshaft, or a failure in the sensor's circuit. (Note: If related to Intake Throttle Valve Actuator, the sensed physical value has exceeded the maximum allowable threshold).

• Steiger tractors
• Magnum tractors
• Maxxum series
• Puma series
• skid steer loaders (SSL)
• compact track loaders (CTL)

1. 1

   For Code 3955 (Camshaft Sensor): Check the offset between the camshaft and crankshaft speed sensors using a diagnostic service tool.

2. 2

   For Code 3955 (Camshaft Sensor): Inspect the camshaft sensor wiring harness for open circuits or shorts to high/low voltage sources.

3. 3

   For Code 3955 (Camshaft Sensor): Inspect the crankshaft signal wheel for physical damage or mechanical misalignment.

4. 4

   For Intake Throttle Valve Actuator: Inspect the harness connector to the intake throttle valve for corrosion or a short circuit to the battery/ground.

5. 5

   For Intake Throttle Valve Actuator: Monitor the sensed physical value via a diagnostic tool to see if the voltage remains stuck above the maximum physical range check.

1. 1

   Disconnect the machine's battery power.

   First step for repairing the Camshaft Position Sensor (Code 3955).

2. 2

   Locate the camshaft position sensor on the engine block and disconnect the harness connector.

3. 3

   If wiring tests confirm the harness is good but the signal remains invalid (above range max / below range min), replace the camshaft sensor.

4. 4

   In rare cases where the signal is still invalid after sensor replacement and wiring checks, the Engine Controller (ECU) itself may need to be replaced.

5. 5

   Clear the fault codes and use a service tool to perform the procedure to restore self-learning parameters.

6. 6

   If repairing the Intake Throttle Valve: Remove the air duct from the intake throttle valve.

7. 7

   Pull the lock operation portion on the connector to release the lock, then disconnect the harness from the intake throttle valve.

8. 8

   Remove the mounting hardware and remove the intake throttle valve assembly from the engine.

9. 9

   Install the replacement valve, reconnect the harness, and reinstall the air duct.

10. 10

    Connect a diagnostic service tool (such as Bosch ESI or Jaltest) to perform the electronic calibrations of the new intake throttle valve.