P0340 Check Engine Code

What's going on

P0340 means the computer is not getting a reliable signal from the camshaft position sensor — or the circuit is out of range. Some vehicles will not start; others run poorly or stall. Wiring at the sensor connector, oil contamination on the sensor, or a failed sensor are common. Timing belt or chain issues can also affect cam correlation on some engines.

Symptoms

• Check engine light with P0340 — may crank no-start on some models
• Stalling or hard restart when hot
• Rough running or reduced power
• Code after timing belt or chain service
• Oil leak soaking the cam sensor connector

Common causes

• Failed camshaft position sensor
• Damaged wiring or connector at the sensor
• Oil contamination from valve cover leak
• Timing belt/chain off one tooth (correlation codes may accompany)
• Aftermarket sensor incorrect air gap

Often sounds like

• P0016 crank/cam correlation — timing mechanical issue
• Crank sensor codes — different circuit, similar no-start

How we check it

1. 1 Oscilloscope or scan data for cam signal presence
2. 2 Inspect connector and oil intrusion
3. 3 Verify timing correlation when sensor and wiring are good

What happens next when you bring it in?

1. 1 Call with whether it is a no-start, a stall, or just the light on.
2. 2 We test the cam signal circuit and timing evidence before swapping the sensor.

Questions we get a lot

What does P0340 mean?

P0340 is “Camshaft Position Sensor Circuit Malfunction.” The ECU did not receive a valid cam position signal from the sensor circuit.

Will P0340 prevent my car from starting?

On some models, yes — crank no-start until the cam signal is restored. On others it runs rough or stalls. Tow in if it will not start reliably.

Related problems

• Check Engine Light
• Car Won't Start
• Honda Timing Belt