P0340 Camshaft Position Sensor A Circuit Malfunction (Bank 1 or Single Sensor)

P0340 points to a camshaft-position sensor A circuit malfunction on bank 1 or a single-sensor setup. It can affect starting, timing control, variable valve timing, and misfire diagnostics.

Code details

Generic OBD-II · P0

System: Ignition / Misfire
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not assume every P0340 is a bad sensor; timing correlation, wiring, and trigger-wheel issues can create the same fault.

Symptoms of P0340

Hard starting, a no-start, or stalling.
Rough running or hesitation.
Check-engine light.

Common causes of P0340

A failed camshaft-position sensor.
Sensor wiring or connector faults.
A damaged reluctor / tone ring.
Timing-chain issues affecting the signal.

Useful checks before replacing parts

Check cam-sensor power, ground, signal, connector fit, and harness damage near the cylinder head.
Compare cam/crank synchronization data and look for timing-chain, belt, or phaser-related companion codes.
Inspect recent service work that may have disturbed sensor wiring or cam timing.

Related OBD-II codes

These nearby ignition / misfire entries can help compare wording and pin down the fault area.