Technical Description of OBD-II Trouble Code
The circuit for the Camshaft Position Sensor “B” on Bank 2 is experiencing intermittent issues.
What does that mean?
This is a generic diagnostic trouble code (DTC) for the powertrain, which applies to all makes and models from around 2003. The specific troubleshooting steps will vary depending on the vehicle.
These vehicles may have a single camshaft in the engine block, or a single (SOHC) or dual (DOHC) overhead camshafts. However, this code specifically relates to the absence of the incoming signal from the camshaft position sensor(s) “B” on Bank 2 at certain times when it should be present. This is an intermittent electrical circuit fault that does not occur constantly. Bank #2 refers to the bank of the engine that does not contain cylinder #1.
The PCM (Powertrain Control Module) uses the Camshaft Position Sensor to determine the accuracy of the Crankshaft Sensor signal, the timing of a given Crankshaft Position Sensor signal in relation to Cylinder #1, and for fuel injector synchronization and start of injection.
Codes P0390 or P0391 may also be present simultaneously with P0394. The only difference between these three codes is the duration of the problem and the type of electrical issue affecting the sensor/circuit/engine controller. Troubleshooting steps may vary depending on the manufacturer, type of camshaft position sensor, and wire colors.
Symptoms
Symptoms of a P0394 engine code may include:
Potential Causes
The typical causes for this code are:
Diagnostic and Repair Procedures
A good starting point is to search for any technical service bulletins (TSBs) related to your specific vehicle. The vehicle manufacturer may have a PCM flash/reprogram available to address this issue, so it’s worth checking before pursuing other troubleshooting steps.
Next, locate both the Camshaft “B” and Crankshaft Position Sensors on your vehicle. Once located, visually inspect the connectors and wiring for any signs of chafing, rubbing, bare wires, burn spots, or melted plastic. Separate the connectors and carefully examine the terminals inside for corrosion, burning, or a greenish color instead of the normal metal color. If necessary, use Electrical Contact cleaner or rubbing alcohol and a plastic bristle brush to clean the terminals. After cleaning, allow them to air dry and apply some dielectric silicone compound where the terminals make contact.
If you have a scan tool, clear the diagnostic trouble codes from memory and see if this code returns. If it does not, then the issue was likely related to the connections.
If the code does return, you will need to test the sensor and its associated circuits. The next steps will depend on whether you have a Hall Effect sensor or a Magnetic Pickup style sensor. You can determine the type of sensor by the number of wires coming from it. A sensor with 3 wires is a Hall Effect sensor, while a sensor with 2 wires is a Magnetic Pickup style sensor.
Hall Effect Sensor
If you have a Hall Effect sensor, disconnect the harnesses going to the Camshaft and Crankshaft Position Sensors. Use a Digital Volt Ohm Meter (DVOM) to test the 5V power supply circuit for each sensor, ensuring that it is receiving power (Red lead to the 5V power supply circuit, black lead to a good ground). If there is no 5 volts to the sensor, repair the wiring from the PCM to the sensor or consider a faulty PCM.
If the power supply circuit is functioning correctly, use the DVOM to check for 5V on each signal circuit going to each sensor, confirming the presence of a signal circuit (Red lead to the sensor signal circuit, black lead to a good ground). If there is no 5 volts to the sensor, repair the wiring from the PCM to the sensor or consider a faulty PCM.
Next, check for a good ground at each sensor. Connect a test light to 12V and touch the other end to the ground circuit going to each sensor. If the test light does not illuminate, there is a problem with the circuit. If the test light does illuminate, wiggle the wiring harness going to each sensor to see if the test light flickers, indicating an intermittent connection.
Magnetic Pickup Style Sensor
If you have a Magnetic Pickup style sensor, you can test the sensor itself to determine if it is functioning properly. Perform the following tests:
Related Camshaft Trouble Codes: P0340, P0341, P0342, P0343, P0345, P0346, P0347, P0348, P0394, P0365, P0366, P0367, P0368, P0369, P0390, P0391, P0392, P0393.
