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P0342 Generic (SAE)

Camshaft Position Sensor A Circuit Low Input (Bank 1 or Single Sensor)

Updated 2026-10-02 · Ignition system & misfires

Severity
Medium
Typical repair cost
50 – 300 EUR
System
Powertrain

What it means

The ECM sees the camshaft position sensor A signal on bank 1 stuck low or producing too few pulses relative to crankshaft rotation. This sensor tells the ECM which cylinder is on its compression stroke and feeds variable valve timing control, so a low signal degrades sequential injection, start-up and cam phasing. Typical causes are a shorted signal wire, a failed Hall sensor or a lost sensor supply.

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Symptoms

  • Extended cranking before start, especially when warm
  • Check engine light on
  • Rough idle and hesitation at light throttle
  • Reduced power with VVT in default position
  • Possible stalling on some engines that rely on the cam signal for sync

Common causes

  1. Failed camshaft position sensor (Hall element dead or output stuck low)
  2. Signal wire shorted to ground through chafed insulation
  3. Missing 5 V or 12 V supply to the sensor from a broken wire or shared-circuit fault
  4. Oil intrusion into the sensor connector through a leaking sensor seal
  5. Excessive air gap or damaged trigger lobe on the cam or VVT phaser wheel
  6. Stretched timing chain altering cam-to-crank correlation (often with P0016)

How to diagnose

  1. Confirm bank 1 and sensor A: bank 1 contains cylinder 1, sensor A is normally the intake cam. Check for companion codes P0016, P0011 or P0335.
  2. At the sensor connector with key on, verify supply voltage (5 V or 12 V depending on design) and ground drop below 0.1 V.
  3. Scope the signal wire while cranking: a Hall sensor should produce a square wave swinging between about 0.3 V and supply with one or several pulses per cam revolution; a line flat near 0 V confirms a low signal.
  4. Unplug the sensor and measure the signal wire to ground: a reading under 100 ohm indicates a harness short; with the sensor plugged back in and the line still low, the sensor itself is at fault.
  5. Pull the sensor and inspect the tip and the trigger wheel for damage, oil sludge or metal; check that the sensor is fully seated and the O-ring is not holding it off its stop.
  6. If wiring and sensor test good, compare cam and crank signals on a dual-channel scope against the manufacturer's reference pattern to rule out mechanical timing drift.

Frequently asked questions

Will the engine run without the cam sensor?

Many engines start in a fallback mode using the crank sensor alone, often with longer cranking and batch injection. Some designs will not start at all.

Is the cam sensor the same as the crank sensor?

No. The crank sensor reads crankshaft speed and position; the cam sensor identifies which cylinder is on compression. They have different mounting positions and often different part numbers even if they look alike.

Related codes

P0340P0341P0343P0344P0016

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