Camshaft Position Sensor B Circuit High Input (Bank 2)
The ECU detected the camshaft position sensor on Bank 2 is sending a voltage signal that's too high, like a stuck throttle pedal sensor that won't drop back down. This prevents the engine computer from accurately timing the intake and exhaust valve openings.
The ECU monitors the analog voltage output from the camshaft position sensor B on Bank 2, expecting it to cycle within a normal range as the cam rotates. When the voltage remains consistently above the upper threshold (typically >4.5V), the ECU interprets this as a circuit malfunction and sets the fault code. The sensor should toggle between low and high states; a stuck high signal indicates either a failed sensor, wiring short, or connector issue.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Sensor voltage output | 0.5–4.5 V (cyclic) | >4.5 V sustained |
| Signal frequency | Synchronous with crankshaft | No transition or stuck high |
Code P0393 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0393 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.