P0335 fault code: Crankshaft Position Sensor 'A' Circuit

Last updated · OBDCode UK editorial

Can I drive with P0335? — Drive only if essential

Limit driving to essential journeys. Avoid long trips and heavy loads. Book diagnosis soon — if the engine will not start, stalls, or feels unsafe, stop and arrange recovery.

P0335 means “Crankshaft Position Sensor 'A' Circuit” — an ignition system and misfire fault in the powertrain. Drive only if essential. The computer is not getting a reliable signal from crankshaft position sensor A. That can mean a no-start, stalling, or a cut while cranking. It is not a knock-sensor fault and not a DIY timing job.

Can I DIY?

Caution — conditions apply. We do not publish DIY repair or strip-down steps for this code on this page. Read codes and observe only; leave the repair to a qualified garage.

Caution — conditions applyDIY boundary
ToolsBasic tools only — for example a household socket set, tyre gauge, or a consumer OBD reader.

Some checks may be possible for a careful DIY driver with the right tools and a safe place to work. Stop if anything feels beyond your skill or kit.

P03xxIgnition system and misfire
MOT fail riskif the warning light stays on

What does P0335 mean?

P0335 is a generic (SAE standard) powertrain code reported by your car’s engine control unit. It sits in the P03xx block, which covers ignition system and misfire. The stored description is “Crankshaft Position Sensor 'A' Circuit”. The code itself tells you which circuit or system tripped the fault — not always the exact part that failed.

How to diagnose P0335 yourself

  1. Confirm P0335 if the socket is live: If the ignition powers the dash, connect a basic OBD-II reader without cranking repeatedly. Note current versus pending P0335, freeze-frame rpm (often 0 rpm), and any camshaft-position or correlation codes. Stop if: The car is in a live carriageway. Move it only if safe, or call recovery. Do not keep cranking a non-starter.
    Generic driver footwell showing a broad OBD-II socket search zone and the usual 16-pin socket shape.
    Park safely and switch off before locating the socket. Its position varies, so use the vehicle handbook and never force or dismantle trim.
  2. Note crank, start, and stall behaviour: From outside the traffic flow, record whether the starter turns the engine, whether it fires, and whether it dies once warm. Do this in open air. Do not spray starting fluid. Stop if: You are on a slope, a public road, or in a closed garage. Headache or nausea with exhaust smell: get fresh air and stop.
  3. Do not attempt timing or sensor fitting: If companion P0016 (crank-cam correlation) or a camshaft-position code is stored, treat timing as professional-only. This page does not publish lock-tool, chain, or sensor-fitting steps. Stop if: A guide asks you for a torque figure, a timing mark procedure, or to support the engine to reach the sensor.

Will P0335 fail an MOT?

An illuminated engine management light is a Major defect at MOT (automatic fail) until the fault is repaired and the light stays off.

Before booking your test, check what usually fails on your car: see our MOT pass rates by make and model, built from 33.1 million DVSA tests.

What the MOT data says

No MOT certificate item corresponds to this code; MOT outcome data cannot be shown.

Related guides

Car diagnostic test cost: compare the scopeUK booking marketplaces currently publish diagnostic averages of about £52–£65. Engine management light on: steady or flashing?A steady engine management light means the computer has stored a fault. Drive with caution and get the code read. A flashing light is different — stop when it is safe. Flashing engine management light and juddering: stop and recoverNo — do not continue the journey. A flashing engine management light with the car juddering is a stop-driving situation: ease off only enough to reach the nearest place of relat… Car turns over but won’t start: safe checks before recoveryNo — while the engine turns but will not start, the car cannot be driven. Stay parked, switch the ignition off and stop repeated attempts. Check only for fuel smell or leakage,…
P0300Random/Multiple Cylinder Misfire Detected P0301Cylinder 1 Misfire Detected P0302Cylinder 2 Misfire Detected P0303Cylinder 3 Misfire Detected P0304Cylinder 4 Misfire Detected P0305Cylinder 5 Misfire Detected P0306Cylinder 6 Misfire Detected P0307Cylinder 7 Misfire Detected

P0335 — quick answers

Is it safe to drive with P0335?

Drive only if essential. Limit driving to essential journeys. Avoid long trips and heavy loads. Book diagnosis soon — if the engine will not start, stalls, or feels unsafe, stop and arrange recovery.

Can I fix P0335 myself?

Caution — conditions apply. We do not publish DIY repair or strip-down steps for this code on this page. Read codes and observe only; leave the repair to a qualified garage. Basic tools only — for example a household socket set, tyre gauge, or a consumer OBD reader.

Will P0335 fail my MOT?

An illuminated engine management light is a Major defect at MOT (automatic fail) until the fault is repaired and the light stays off.

Fault-code identifiers are standard diagnostic facts. Their explanations and diagnostic guidance on this site are original editorial summaries, not reproduced SAE wording. MOT defect rules reflect the DVSA MOT inspection manual (2026). This page is general guidance for UK drivers, not a substitute for a professional diagnosis.