P0393
UniversalCamshaft Position Sensor B Circuit High Input (Bank 2)
The engine computer has detected a signal that is higher than expected in the circuit for camshaft position sensor B on bank 2. The sensor reports camshaft position so the computer can coordinate engine timing and operation. This code identifies a circuit condition; it does not prove the sensor itself has failed.
⚠️ Before You Begin (Safety First)
If the engine stalls, becomes difficult to control, or runs very poorly, stop in a safe place and arrange for diagnosis rather than continuing to drive. If the warning light is on but the vehicle runs normally, drive cautiously and have the fault checked soon.
Common Symptoms
- There may be no noticeable symptoms, especially if the engine computer can still use other timing information.
- The engine may crank longer than usual or be difficult to start if the computer cannot reliably determine camshaft position.
- The engine may run roughly, hesitate, or lose power if timing-related control is affected.
- The engine may stall in some cases if the signal becomes unreliable while running.
- The check-engine light may be illuminated.
Common Causes
- A fault within camshaft position sensor B on bank 2 may produce an abnormally high circuit signal.
- Damaged, rubbed-through, or improperly repaired wiring may cause the signal circuit to read high.
- A loose, corroded, contaminated, or damaged connector may disrupt the sensor circuit.
- A circuit fault involving its power, ground, or signal wiring may cause the detected condition; the applicable circuit design varies by vehicle.
- An engine timing or signal-related problem may affect the reported camshaft position and should be considered if circuit checks do not identify a fault.
Diagnostic Steps
- Note whether the engine is hard to start, running roughly, losing power, or stalling; these details help a technician assess the fault.
- Check for other stored diagnostic codes and record them before clearing anything, because related codes can help narrow the diagnosis.
- With the engine off and cool, visually inspect accessible wiring and connectors for looseness, corrosion, oil contamination, or obvious damage. Do not pull on wires or disconnect components while the engine is running.
- Use the owner's manual to identify the correct bank and sensor only if the vehicle-specific information is available; sensor locations and bank identification vary by engine.
- If wiring damage is not obvious or the fault returns, arrange circuit testing using the vehicle's wiring diagram rather than replacing the sensor based on this code alone.
When to Call a Professional
A technician can check scan data and related codes, inspect the sensor connector and wiring, and test the circuit using the vehicle's wiring diagram. Signal analysis can help distinguish a sensor fault from a wiring, connector, power, ground, or engine-timing issue. Test procedures and expected values depend on the model, year, and engine.
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Commonly Asked Questions
Does P0393 prove that camshaft position sensor B needs replacement?
No. It reports a high-input condition in that sensor's circuit. The sensor, connector, wiring, or another related issue may be responsible, so testing is needed before choosing a repair.
What does “high input” mean in this code?
The engine computer detected a circuit signal higher than expected for camshaft position sensor B on bank 2. The exact cause and circuit behavior depend on the vehicle.
Can I keep driving with P0393?
If the vehicle runs normally, cautious driving to arrange diagnosis may be reasonable. Stop safely and seek assistance if it stalls, becomes difficult to control, or runs very poorly.
Why might the engine have no symptoms?
The computer may still have enough information to keep the engine running normally, or the fault may be intermittent. A lack of symptoms does not identify the cause or rule out the need for diagnosis.
How is the cause distinguished from a failed sensor?
A technician can inspect the connector and wiring, review scan data and related codes, and test the circuit and signal using vehicle-specific service information.
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