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P0346




DTC P0341, P0346, P0366, or P0391 (LF1)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptors
DTC P0341
- Intake Camshaft Position Sensor Performance Bank 1

DTC P0346
- Intake Camshaft Position Sensor Performance Bank 2

DTC P0366
- Exhaust Camshaft Position Sensor Performance Bank 1

DTC P0391
- Exhaust Camshaft Position Sensor Performance Bank 2

Diagnostic Fault Information





Circuit/System Description

The 4X camshaft position sensor circuits consist of an engine control module (ECM) supplied 5 V reference circuit, low reference circuit, and an output signal circuit. The camshaft position sensor is an internally magnetic biased digital output integrated circuit sensing device. The sensor detects magnetic flux changes of the teeth and slots of a 4-tooth reluctor wheel attached to the camshaft. As each reluctor wheel tooth rotates past the camshaft position sensor, the resulting change in the magnetic field is used by the sensor electronics to produce a digital output pulse. The sensor returns a digital ON/OFF DC voltage pulse of varying frequency, with 4 varying width output pulses per camshaft revolution that represent an image of the camshaft reluctor wheel. The frequency of the camshaft position sensor output depends on the velocity of the camshaft. The ECM decodes the narrow and wide tooth pattern to identify camshaft position. This information is then used to determine the optimum ignition and injection points of the engine. The ECM uses the cylinder 1 intake camshaft position sensor to determine injector and ignition system synchronization. Also, the cylinder 1 intake camshaft position sensor is used to determine camshaft to crankshaft relationship, to control camshaft phasing, and for limp-home operation.

Conditions for Running the DTC

* DTCs P0335, P0336, P0641, P0651, or P0697 are not set.
* The engine is cranking or running.
* The DTC runs continuously when the above conditions are met.

Conditions for Setting the DTC

* The ECM detects that the engine has started, but has received either of the following during the first engine revolution:

- Less than or more than 4 camshaft position sensor pulses, if equipped with an automatic transmission
- Less than 4 or more than 8 camshaft position sensor pulses, if equipped with a manual transmission

* The ECM detects that the engine is running, but receives less than 398 camshaft position or more than 402 camshaft position sensor pulses per 100 engine cycles in 800 of 1000 engine cycles.

Action Taken When the DTC Sets

* DTCs P0341, P0346, P0366, and P0391 are Type B DTCs.
* The camshaft position actuator is commanded to the Home or Parked position.
* The ignition system defaults to a failed camshaft position sensor based on the crankshaft position sensor.

Conditions for Clearing the MIL/DTC

* DTCs P0341, P0346, P0366, and P0391 are Type B DTCs.
* With a DTC set, the engine may crank for an extended period of time at start-up.

Diagnostic Aids

* With a DTC set, the engine may crank for an extended period of time at start-up.
* The cylinder 1 intake camshaft position sensor is used for injector and ignition system synchronization. A stalling condition will occur if the CMP sensor signal is intermittent and a DTC will not set. Inspect all cylinder 1 intake camshaft position sensor circuits for poor connections.

Reference Information
Schematic Reference

Engine Controls Schematics (LAU) ([1][2]Electrical Diagrams)Engine Controls Schematics (LF1) ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Electronic Ignition System Description (Electronic Ignition System Description)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Engine Control Module Scan Tool Information (LF1,LFW) (Scan Tool Testing and Procedures)Engine Control Module Scan Tool Information (LAU) (Scan Tool Testing and Procedures) for scan tool information

Circuit/System Verification

1. If DTC P0340, P0345, P0365, or P0390 are also set, diagnose those DTCs first
2. With the ignition OFF, inspect the engine wiring harnesses carrying the B23 camshaft position sensor circuits for the following conditions:

* Close routing of aftermarket electrical equipment
* Close to solenoids, motors, and relays

• Correct any wire harness routing or component placement conditions if it is determined to be a possible source of electrical interference.

3. Observe the following scan tool parameters are all incrementing:

* Exhaust Camshaft Position Active Counter Bank 1
* Intake Camshaft Position Active Counter Bank 1
* Exhaust Camshaft Position Active Counter Bank 2
* Intake Camshaft Position Active Counter Bank 2

4. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Engine idling, move the related harnesses/connectors of the B23 camshaft position sensor while monitoring the scan tool Camshaft Position Variance parameter. The Camshaft Position Variance parameter should not change when moving the harness/connectors.

• If the above condition exists, repair the harness/connectors as necessary.

2. Ignition OFF, inspect the B23 camshaft position sensor for correct installation.

• If the B23 camshaft position sensor is loose, inspect the sensor and the O-ring for damage and replace as necessary.

3. Disconnect the harness connector at the B23 camshaft position sensor.
4. Ignition OFF, all vehicle systems OFF, this may take 2 minutes, test for less than 5 ohm between the low reference circuit terminal B and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.

5. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal A and ground.

• If less than the specified range, test the 5 V reference circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
• If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

6. Test for 4.8-5.2 V between the signal circuit terminal C and ground.

• If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

7. Ignition OFF, connect a 3 A fused jumper wire to the camshaft position signal circuit terminal C.
8. Ignition ON, momentarily touch the end of the fused jumper wire to ground while monitoring the scan tool camshaft position active counter. The camshaft position active counter should increment.

• If the camshaft position active counter does not increment, replace the K20 ECM.

9. If all circuits test normal, replace the B23 camshaft position sensor.

Component Testing

Note: You must perform the Circuit/System Testing before proceeding with Component Testing.

1. Inspect the B23 camshaft position sensor for looseness and correct installation. Remove the camshaft position sensor from the engine and inspect the sensor and the O-ring for damage.

• If the sensor is loose, incorrectly installed, or damaged, repair or replace the B23 crankshaft position sensor.

2. Connect the camshaft position sensor connector to the camshaft position sensor. Turn ON the ignition, with the engine OFF.
3. Ignition ON, observe the applicable camshaft position active counter parameter with a scan tool. Pass a steel object by the tip of the sensor repeatedly. The camshaft position active counter parameter should increment.

• If the function does not perform as specified, replace the B23 camshaft position sensor.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Camshaft Position Sensor Replacement - Bank 2 (Left Side) Exhaust (Camshaft Position Sensor Replacement - Bank 2 (Left Side) Exhaust)
* Camshaft Position Sensor Replacement - Bank 2 (Left Side) Intake (Camshaft Position Sensor Replacement - Bank 2 (Left Side) Intake)
* Camshaft Position Sensor Replacement - Bank 1 (Right Side) Exhaust (Camshaft Position Sensor Replacement - Bank 1 (Right Side) Exhaust)
* Camshaft Position Sensor Replacement - Bank 1 (Right Side) Intake (Camshaft Position Sensor Replacement - Bank 1 (Right Side) Intake)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming

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