P0343: Camshaft Position Sensor A Circuit High Input (Bank 1 or Single Sensor)

What does P0343 mean?

The bank 1 camshaft A signal is above its permitted electrical level. An open ground or a signal short to the reference supply can hold the input high and hide the normal cam pulses.

Generic OBD-II definition: Camshaft Position Sensor A Circuit High Input (Bank 1 or Single Sensor). Confirm applicability in your vehicle service information.

Common causes

• Signal shorted to supply voltage
• Open sensor ground or signal connection
• Internally failed cam sensor

Symptoms

• Bucking or surging
• Stalling that may be intermittent
• Possible failure to restart

Diagnostic focus

High input is not advanced cam timing. Do not confuse this electrical fault with P0011; the two codes monitor different parts of the timing system.

Can I keep driving with P0343?

Severity: High A position-signal fault can cause stalling or failure to restart. Avoid normal use until diagnosed; arrange towing if the engine stalls, runs severely rough, or will not start reliably.

If the check engine light is flashing or the car runs badly, stop driving and have it checked.

Typical fixes

• Inspect the bank 1 sensor ground and connector
• Check the signal wire for short-to-power
• Compare waveform at the sensor and controller if needed

Sources & review

• OBD-Codes.com: P0343
• TroubleCodes.net: generic code definitions

Definitions and diagnostic background checked 2026-11-06. Generic guidance, not a substitute for the service procedure for your exact year, engine, and transmission.