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P0390 is a diagnostic trouble code (DTC) for "Camshaft Position Sensor “B” Circuit (Bank 2)". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $69.99. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
The P0390 code is stored if the powertrain control module (PCM) does not detect the camshaft position sensor signal within a few seconds of cranking. This code is specific to sensor “B,” which, in general, is the exhaust camshaft sensor. In most cases, this code is almost identical to a P0345 code, and the two may appear simultaneously.
When the P0390 code is stored, it indicates that the PCM has detected an abnormal or incorrect voltage reading from sensor “B” on the camshaft position sensor circuit in engine bank 2. An electro-magnetic sensor, when sensor “B” is working properly, the teeth on the camshaft will interrupt its magnetic field, giving the PCM data about the camshaft’s position. The PCM then uses this data to calculate ignition timing and fuel delivery. If the input is incorrect, these systems cannot get the proper calculations.
In most cases, the P0390 code is stored when engine fluids (such as oil) leak onto wiring, sensors, or electrical connectors. This will generally cause the circuits to be shorted or opened, or it can cause connectors to loosen. In other cases, the cause could be:
In addition to illumination of the Check Engine light, when a P0390 code is stored, other symptoms may occur, including the engine:
Upon detecting the P0390 code with an OBD-II scanner, a mechanic will then begin a visual inspection of the wires and connectors in the camshaft position sensor’s circuit. After repairing or replacing any damaged items in this system, they will clear the code and operate the vehicle. If the code remains clear, the problem is solved. If not, they will then proceed to take further diagnostic steps to inspect and test the camshaft position sensor and the crankshaft position sensor, as well as the PCM if necessary.
Assuming that the camshaft position sensor is the problem without first checking for fluid leaks and other damage to wiring or connectors will often make this problem more expensive and time consuming than it should be.
In most cases, a problem with the camshaft position sensor will not stop a vehicle from running, but it can make it very difficult and/or dangerous to operate. If your engine stalls while you’re on the road, or if your vehicle is running very rough, the problem could cause a hazard to yourself and others. Furthermore, because the camshaft position sensor “B” provides the PCM with data for fuel delivery and ignition timing, a malfunctioning sensor or a short in the sensor’s wiring could cause problems with fuel efficiency and/or starting the vehicle reliably.
Most commonly, the P0390 code can be resolved and cleared by replacing, repairing, or cleaning wiring or electrical connectors that have been damaged or that have come loose due to engine fluid leaks. Other repairs include:
If the cause of the P0390 code was an engine fluid leak that caused damage to the wiring, connectors, or any other part of the circuit for the camshaft position sensor, it’s important to determine the cause of the leak. Otherwise, more fluid is likely to leak onto these and other parts, causing even more damage.
YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.