P0335: Crankshaft Position Sensor 'A' Circuit Malfunction

Can I keep driving?

What to do right now

1. 1Pull over safely to the side of the road or into a car park if the engine cuts out or stumbles.
2. 2Switch off the ignition and do not attempt repeated, prolonged cranking, as this will quickly drain your 12-volt battery.
3. 3If the car cut out while hot, allow the engine bay to cool down for twenty minutes, as failing sensors often temporarily work again once cool.
4. 4Arrange roadside assistance or recovery rather than attempting to drive in fast or heavy traffic.

Likely causes

Most likely first.

1. Likely

   Failed crankshaft position sensor

   The internal copper winding or electronic chip inside the sensor breaks down from years of engine heat and vibration, causing signal loss when warm.

2. Possible

   Damaged wiring or corroded connector

   The sensor sits low down near the road and exhaust, leaving its wiring harness exposed to road spray, salt corrosion, oil leaks, and melted insulation.

3. Possible

   Damaged or dirty reluctor ring

   The toothed wheel that the sensor reads can gather metallic debris, crack, or suffer missing teeth, breaking the magnetic pulse sent to the computer.

4. Rare

   Severely stretched timing chain or belt issue

   Significant slack or jumped timing can throw the crankshaft and camshaft signals so far out of sync that the computer flags a circuit fault.

What you can check yourself

Park somewhere safe and level, engine off, before you start.

1. 1

   Watch the rev counter while cranking

   Turn the key to crank the engine and watch the tachometer needle on your instrument cluster. If the needle does not lift slightly from zero while the starter turns, the engine computer is almost certainly receiving no crank signal.

2. 2

   Check the battery terminal connections

   With the engine off, open the bonnet and check that both 12-volt battery terminals are tight and free of white powdery corrosion. Low system voltage during cranking can corrupt the sensor signal.

3. 3

   Inspect the sensor wiring harness

   Locate the crankshaft sensor near the bottom of the engine block or gearbox bell housing once the engine is cool. Check the wiring for frayed insulation, contact with hot exhaust pipes, or an oil-soaked electrical plug.

4. 4

   Inspect the sensor connector plug

   Gently press the plastic tab and unclip the connector if you can safely reach it. Check inside for green corrosion, bent pins, or engine oil contamination, then push it back until it clicks firmly.

Typical prices in Ireland (€) and the UK (£), from an independent garage up to a main dealer. The total cost depends mainly on how accessible the sensor is, as some sit behind engine covers or require gearbox removal to access the reluctor ring.

When to go to a garage

• The car cuts out unpredictably whilst driving and leaves you stranded without power steering.
• The engine cranks strongly but will not fire at all, even after letting it cool down.
• Replacing the sensor fails to clear the fault code, pointing to a wiring break or reluctor ring damage.
• The sensor is buried behind the timing belt cover or deep inside the transmission housing.

Questions drivers ask

Test rules here are for the National Car Test in Ireland (NCT) and the MOT in the UK. Elsewhere, check the regulations of your own country or state before going for a vehicle test.