P0393 — Camshaft Position Sensor B Circuit High (Bank 2)
Moderate severityWhat it means
P0393 is stored when the engine control unit sees a fault involving the camshaft position sensor B circuit on bank 2. Sensor B is the second camshaft position sensor on bank 2 (for example on the exhaust cam of a dual-VVT engine); the control unit uses it for valve-timing control and sequencing. A “high” reading means the signal is pinned near the top of its range — often an open circuit, a lost ground, or a short to voltage.
Common symptoms
- The live reading sits abnormally high or maxed out
- Hard starting or rough running
- Loss of power or VVT-related codes
- Possible stalling
Likely causes
- Open signal or ground wire
- Signal wire shorted to a voltage supply
- A faulty camshaft position sensor B
- A wiring/connector fault or a worn tone ring
What to check first
- Check for an open circuit or missing ground at the sensor connector
- Inspect the sensor B connector and wiring
- Check for cam/crank correlation codes and timing noise
Can you keep driving?
May cause hard starting or stalling; if it runs poorly, avoid driving until it is checked.
Frequently asked questions
What is the most common cause of P0393?
The most likely cause is: Open signal or ground wire. Several other faults can set P0393 as well, so confirm the real cause with live data and the checks above before replacing any parts.
Can I just clear P0393 and keep driving?
Clearing P0393 with an OBD2 scanner turns the warning light off, but if the underlying fault has not been repaired the code will usually come back within a few drive cycles. Fix the cause first, then clear the code to confirm the repair worked.
How serious is P0393?
P0393 is a moderate-severity code. The car is often still drivable, but have it diagnosed soon — the underlying problem can get worse and it may fail an emissions test.
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