P0394 code definition
When an OBD-II scanner detects the P0394 code, it indicates that the PCM has detected an intermittently incorrect voltage reading from the camshaft sensor circuit B in engine bank 2.
What the P0394 code means
In order for the engine control module, or ECM, to control the fuel injection and ignition within the engine, it requires data regarding the rate at which the camshaft is spinning. This data is provided by the camshaft position sensor, which reads the change in the magnetic field of the camshaft operation and translates that information into voltage. If the voltage does not match what the manufacturer’s specifications say that it should be for the current circumstances, the PCM will assume that there is an issue with the sensor and store the P0394 code.
What causes the P0394 code?
The camshaft and sensor are both made up of multiple parts that could create an issue for the voltage reading. Therefore, the root cause of the P0394 could be any of the following:
- Faulty camshaft position sensor
- Leaking oil or engine fluids
- Open or shorted camshaft position sensor
- Poor electrical connection in the camshaft position sensor circuit
- Dead or weakened battery
- Faulty starting system circuit
- Faulty starter motor
- Shorted, grounded, loose, or faulty electrical components such as wiring and connectors
- PCM failure, in rare cases
What are the symptoms of the P0394 code?
How does a mechanic diagnose the P0394 code?
Once the P0394 code has been verified with the scanner, the technician should perform a visual inspection of all the wiring, connectors, and other electrical components. If any damaged elements appear, they should be replaced, reconnected, or repaired as necessary. The mechanic should then clear the P0394 code from the PCM memory, and retest the system. If the code returns, they will then move on to other repairs to address issues within the camshaft position sensor.
Common mistakes when diagnosing the P0394 code
Most often, technicians will assume that the issue lies with a faulty sensor, and replace the part without performing a thorough diagnosis on the entire system. OEM sensor components don’t fail as frequently as other issues, and the code pertains to the entire circuit, which could indicate a fault at many other specific parts.
How serious is the P0394 code?
If the P0394 code is being detected, it indicates a very serious issue that should be addressed right away. The problem relates directly to how well the ignition and fuel injection functions operate, and can have significant effect on the vehicle overall.
What repairs can fix the P0394 code?
In order to repair the cause of the P0394, there are many things that a mechanic should do in order to properly diagnose and address the issue. These steps may include:
- Inspecting and repairing all electrical components during the initial diagnosis.
- Replacing a faulty camshaft position sensor.
- Addressing a leak in oil or engine fluids, and replacing any wiring or electrical components that were affected by the leak.
- Repairing or replacing open or shorted camshaft position sensor.
- Recharging or replacing a dead or weakened battery.
- Replacing a faulty starting system circuit.
- Repairing or replacing a faulty starter motor.
- Replacing a faulty PCM in very rare cases.
After each possible repair is performed, it is important to clear the code from the PCM and retest the system, to confirm that the fix did or did not address the issue.
Additional comments for consideration regarding the P0394 code
Manufacturers recommend replacing crankshaft components at the same time that any camshaft components are replaced. These components work as a team, and perform better when they have similar amounts of wear.
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