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P0343 – Camshaft Position Sensor Circuit High Input (OBD2)

P0343 means "Camshaft Position Sensor Circuit High Input". The voltage in the camshaft position sensor circuit is above the permitted maximum. For most sensors this points to an open signal or ground wire – the signal "floats" up to the reference voltage – or to a short to voltage.

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P0343 quick summary

Fault codeP0343
MeaningCamshaft Position Sensor Circuit High Input
SystemPowertrain (Engine & Transmission)
VehiclesGeneric OBD2
SeverityMedium
Can I drive?Usually yes, but expect longer cranking, less power and possibly limp mode. If the code appears together with timing correlation codes or a rattling chain, stop driving until the timing has been checked.
Repair cost€25 – €300

How the camshaft position sensor works

The camshaft position sensor tells the engine control unit which cylinder is on its compression stroke and, on engines with variable valve timing, the actual camshaft position.

The crankshaft turns twice for every turn of the camshaft, so the crankshaft signal alone cannot tell whether a piston at top dead centre is on its compression or exhaust stroke. The camshaft sensor solves this by reading a trigger wheel or special lobes on the camshaft. Most modern camshaft sensors are Hall sensors with a 5 V or 12 V supply.

Engines with variable valve timing often have one sensor per camshaft – intake (A) and exhaust (B), on V engines per bank. The control unit compares camshaft and crankshaft signals to measure the actual camshaft adjustment.

If the camshaft signal is lost, many engines still start, but it takes longer because the control unit has to guess the firing order. Power may be reduced and variable valve timing is switched off. Causes include a failed sensor, wiring problems, oil in the connector, and – importantly – a stretched or jumped timing chain or belt.

On VAG vehicles (VW, Audi, Škoda, Seat, Cupra), VCDS and older VAG testers can show this code as the five-digit VAG code 16727 (P0343). Both numbers mean the same fault.

Symptoms of P0343

  • Long cranking before the engine starts
  • Check Engine light on
  • Reduced power, limp mode
  • Rough idle or occasional stalling
  • Higher fuel consumption

Most common causes of P0343 (most likely first)

Mechanic's Pro Tip

Swap the intake and exhaust camshaft sensors (if they are identical) and clear the codes. If the code moves from sensor A to sensor B, the sensor is faulty; if it stays, look at wiring or timing.

  1. 1.Open circuit in the signal or ground wire

    Most likely

    A loose ground connection is a very common cause.

  2. 2.Signal wire shorted to the 5 V reference or battery voltage

  3. 3.Faulty camshaft position sensor

  4. 4.Oil in the sensor connector

    A leaking sensor O-ring lets oil wick into the connector and harness.

  5. 5.Wiring or connector fault

    Broken wires, corroded pins or a missing 5 V/12 V supply.

  6. 6.Stretched or jumped timing chain/belt

    Changes the relationship between camshaft and crankshaft signals.

  7. 7.Damaged trigger wheel

    A loose, bent or wrongly fitted trigger wheel on the camshaft.

Step-by-step diagnostic guide

  1. 1

    Read codes

    Read all codes. Correlation codes such as P0016–P0019 alongside the sensor code point to timing chain or belt problems rather than the sensor.

  2. 2

    Check signal and ground

    With the ignition on and the camshaft position sensor plugged in, back-probe the signal and ground wires. A signal stuck at reference or battery voltage points to an open ground/signal wire or a short to voltage.

    Multimeter: Ground wire to battery negative: below about 0.1 V. Signal stuck at about 5 V (or 12 V) = open or short to voltage.

  3. 3

    Inspect connector and O-ring

    Check the connector for oil and corrosion and the sensor O-ring for leaks.

  4. 4

    Check supply, ground and signal

    With the ignition on, check the supply and ground; while cranking, check that the signal switches.

    Multimeter: Supply typically 5 V or 12 V; signal switching between about 0 V and the supply voltage.

  5. 5

    Compare with the crankshaft signal

    On an oscilloscope, display camshaft and crankshaft signals together and compare the pattern with a known-good reference to rule out timing problems.

  6. 6

    Replace and verify

    Replace the sensor or fix the wiring, clear codes and confirm that the engine starts quickly and the code does not return.

Frequently asked questions

Can I keep driving with P0343?

Usually yes, but expect longer cranking, less power and possibly limp mode. If the code appears together with timing correlation codes or a rattling chain, stop driving until the timing has been checked.

How much does it cost to fix P0343?

Typical repair costs are 25 € – 300 €, depending on the cause and the vehicle. The most common fixes are: open circuit in the signal or ground wire; signal wire shorted to the 5 V reference or battery voltage; faulty camshaft position sensor. Always confirm the cause with the tests above before buying parts.

Will a bad camshaft sensor stop the engine?

Usually not while running, but it can cause longer cranking, rough running and limp mode. Some engines will not start at all without the camshaft signal.

Can a timing chain cause camshaft sensor codes?

Yes. A stretched chain or jumped belt changes the camshaft position, which can set sensor range/performance or correlation codes even with a healthy sensor.

What is the difference between P0343 and similar codes?

P0343 belongs to a group of codes for the same component that differ in the type or location of the fault: P0340 – Camshaft Position Sensor Circuit Malfunction; P0341 – Camshaft Position Sensor Circuit Range/Performance; P0342 – Camshaft Position Sensor Circuit Low Input; P0344 – Camshaft Position Sensor Circuit Intermittent; P0345 – Camshaft Position Sensor A Circuit (Bank 2); P0346 – Camshaft Position Sensor A Circuit Range/Performance (Bank 2). The tests on this page apply to the whole group; the type of fault tells you where to start.

Related fault codes

This guide is for information only. Working on vehicles can be dangerous — if you are unsure, have the car checked by a qualified mechanic. Values can differ between model years; always check the manufacturer's repair information.