P0343 Camshaft Position Sensor A Circuit High Bank 1 or Single Sensor

Investigate soon

The voltage on this circuit is sitting near battery voltage. Typically a short to a positive feed, or a disconnected sensor floating high.

Can you drive it? The engine light will stay on and the car may run in a reduced-power mode. Read the freeze-frame data to see the conditions the fault was logged under.

The definition

P0343: Camshaft Position Sensor A Circuit High Bank 1 or Single Sensor.

P0343 is a powertrain code (the engine or gearbox), defined by the SAE standard - it means the same thing on any make of car, and any generic OBD-II reader will decode it.

What to check first

Cheapest and fastest checks first:

Unplug the sensor and check whether the signal falls. If it stays high, suspect the wiring rather than the sensor.
Check the earth path - a missing earth makes a sensor read high.

What actually causes this on a VAG

Same camshaft sensor on bank 1, but here the ECU is seeing the signal line sitting higher than it should. Most of these Hall sensors work by having the ECU hold the signal wire up while the sensor pulls it down as the cam turns, so on that arrangement an open circuit - a broken wire, a dead sensor, or a plug that isn't home - looks exactly like "circuit high". A short to a live wire will do it too. The usual symptoms are long cranking, an occasional refusal to start and rough running, though the car will often still drive.

Most likely causes, in order

Connector not seated, or a broken wire. Check the plug is clipped fully home and the pins are clean and tight, then look along the lead for chafing or a break. This is especially likely if anything has been done on top of the engine lately - coil packs, cam cover gasket, injectors - because the sensor plug is easy to knock off or leave half-connected.
The sensor has failed. A sensor that's gone open circuit internally produces this code and no signal at all. Heat-related failures are common, so a fault that appears once the engine is hot points this way.
Missing supply or earth to the sensor. If the sensor's feed or earth has gone, the signal line can read high even though the sensor itself is fine. Look for other sensor codes stored at the same time and check the shared supply and earth points rather than condemning the sensor.
Short to positive in the loom. Less common, but a signal wire rubbed through against a live wire will hold the circuit high permanently. Trace the loom where it passes brackets and hot components.

Worth knowing: Start at the plug, not the parts shelf. An open circuit and a dead sensor produce the same code, so a connector that isn't fully clicked in - very common after work on top of the engine - looks identical to a failed sensor.

Reading the code is the easy part

A code names the circuit that complained. What tells you why is watching the sensor behind it while the engine runs — and that is where a code reader stops and a diagnostic tool starts.

VAGPULSE reads every module in a VW, Audi, Skoda or SEAT — not just the engine — shows the live measuring blocks behind this fault, gives you the freeze-frame conditions it was logged under, and clears it once you have fixed it. It also does what a generic OBD reader cannot on a VAG: service resets, coding, adaptations, and Stage 1–3 flashing with your original file saved first.

$249 once. No subscription, unlimited cars. Windows 10/11.

See VAGPULSE — $249 Look up another code

Software downloads instantly · cable ships September 30 · cable guarantee — refund if it won't connect

Prefer to work on your phone? The VAGPULSE Android app is a free download and its demo mode runs against a sample car with no hardware at all, so you can see exactly what it reads before spending anything. Reading your car with it needs the VAGPULSE cable, which comes with the licence.

Common questions

What does P0343 mean?

P0343 means Camshaft Position Sensor A Circuit High Bank 1 or Single Sensor. The voltage on this circuit is sitting near battery voltage. Typically a short to a positive feed, or a disconnected sensor floating high.

Can I drive with P0343?

The engine light will stay on and the car may run in a reduced-power mode. Read the freeze-frame data to see the conditions the fault was logged under.