P0393 indicates the powertrain control module (PCM) detected an abnormally high voltage signal from the camshaft position sensor B on Bank 2 (the engine bank opposite cylinder #1). The sensor is failing to provide a proper signal, which can disrupt engine timing and fuel injection scheduling.
The sensor itself has internal failure causing it to output consistently high voltage. This is the most common cause and the sensor typically requires replacement.
The signal wire, ground wire, or reference voltage wire has a short to battery power, causing artificially high readings at the PCM.
Oxidation, bent pins, or broken wires at the sensor or PCM connector can create high-resistance connections that mimic high voltage conditions.
Metal debris, oil fouling, or coolant contamination on the magnetic tip of the sensor can cause abnormal signal output.
Excessive timing chain stretch or a jumped timing belt can place the cam gear in a position that produces anomalous sensor readings.
The PCM itself may have a failed input circuit, but this is rare. PCM failure should only be considered after all other causes are definitively ruled out.
In many V-type engines, Bank 2 refers to the secondary bank (opposite cylinder #1), which often contains the exhaust camshaft. In some inline engines, Bank 2 may indicate the rear camshaft or exhaust camshaft depending on the design.
Driving is not recommended. The engine may stall unexpectedly, fail to start, or run poorly, potentially leaving you stranded. The vehicle should be diagnosed and repaired promptly.
No. While some repair shops may suggest PCM replacement, this is almost never the correct fix. The camshaft position sensor, wiring, or connectors are the actual cause in the vast majority of cases. PCM failure for this specific code is extremely rare.
No. Once P0393 sets, the fault is persistent. The underlying hardware issue must be repaired; clearing the code without fixing the cause will result in the code returning.