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P0343: Camshaft position sensor A circuit high input (bank 1)

The ECU sees a camshaft sensor signal above what is possible. Usually a wire carrying voltage where it should not, a bad earth or the sensor.

Code P0343 at a glance
CodeP0343
SystemEngine and transmission
GroupP03xx, Ignition and misfires
TypeGeneric: it means the same on every make
Can you keep driving?With care

What P0343 means

The camshaft sensor tells the ECU which stroke each cylinder is on, so it can inject at the right moment and control variable valve timing if fitted. High input means the ECU is reading a voltage above what is possible, almost always from an electrical problem. Bank 1 is the side of the engine with cylinder 1; on inline engines it is the only bank. Which sensor is "A" is up to each manufacturer (often the intake cam is A and the exhaust cam is B).

Most common causes

  • Moisture or corrosion in the connector
  • Sensor earth broken or poorly connected
  • Signal wire touching another live wire
  • Failed sensor
  • ECU fault (rare)

Symptoms

  • Longer cranking before the engine starts
  • Less power or slower response
  • Slightly rough idle
  • Engine warning light on

Can you drive with P0343?

With care You can usually keep driving, as the ECU can manage using the crankshaft sensor, but the engine is down on power and may be hard to start. Get it checked soon.

How to check it

Check whether the sensor connector has oil or moisture inside: a leak past the sensor seal can let oil into the connector and trigger this code.

How to read and clear P0343 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0343 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

P0343 is a generic code, so it means the same on any make, for example on Abarth, Citroën, Hyundai, Mini, Seat, Volvo. See what Final OBD does on your car in makes and models.

What does code P0343 mean?

The camshaft sensor tells the ECU which stroke each cylinder is on, so it can inject at the right moment and control variable valve timing if fitted. High input means the ECU is reading a voltage above what is possible, almost always from an electrical problem. Bank 1 is the side of the engine with cylinder 1; on inline engines it is the only bank. Which sensor is "A" is up to each manufacturer (often the intake cam is A and the exhaust cam is B).

Can you drive with P0343?

You can usually keep driving, as the ECU can manage using the crankshaft sensor, but the engine is down on power and may be hard to start. Get it checked soon.

How do you clear P0343?

With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0343 comes back.