```html P0335 Code Meaning UK | Crankshaft Position Sensor Circuit | Motor Vehicle Expert
Motor Vehicle Expert
OBD fault code guide

P0335 Code Meaning UK

P0335 means “Crankshaft Position Sensor Circuit”. In plain English, the engine computer is not receiving the crankshaft position signal it expects. This signal is critical because the ECU uses it to know engine speed, crank position, ignition timing and fuel injection timing. A P0335 fault can cause crank-no-start, cutting out, stalling, misfires or sudden loss of engine power.

📅 Updated June 2026 🇬🇧 UK diagnostic guide 🛠 Crank sensor circuit fault
Quick answer Fault codes hub Cranks but won't start
✓ P0335 meaning ✓ No-start symptoms ✓ UK repair costs ✓ MOT-aware advice
Quick answer Meaning Symptoms Causes Diagnosis No-start advice Repair costs Can you drive? MOT impact Related guides FAQs
Quick answer

What does P0335 mean?

P0335 means the ECU has detected a problem with the crankshaft position sensor circuit. The crankshaft sensor tells the ECU how fast the engine is turning and where the crankshaft is positioned. Without that signal, the ECU may not know when to fire the injectors or ignition system, which is why P0335 can cause a car to crank but not start.

Most likely area

Crankshaft position sensor, wiring, connector, reluctor ring, sensor gap, signal circuit or ECU input.

Urgency

High if the car cuts out, stalls, will not start, misfires badly or loses power suddenly.

MOT risk

Can affect emissions, warning light status, running quality and whether the car can be tested properly.

Code meaning

P0335 — Crankshaft Position Sensor Circuit

The full description is usually P0335 Crankshaft Position Sensor A Circuit. It means the ECU is not seeing the crankshaft signal it expects. This could be because the sensor has failed, the wiring is damaged, the connector is corroded, the sensor signal is weak, or the reluctor ring is damaged.

The crank sensor is one of the most important engine sensors. On many vehicles, if the ECU loses the crank signal, the engine may stop immediately or refuse to start.

Mechanic view

Why P0335 is a proper no-start code

A lot of fault codes still allow the engine to run. P0335 is different. If the ECU cannot see engine speed or crankshaft position, it may not trigger spark or fuel injection correctly.

A classic real-world symptom is a car that cuts out when hot, refuses to restart, then starts again after cooling down. That often points towards a crank sensor that fails when heat affects it.

Symptoms

Common symptoms of a P0335 code

P0335 can cause serious driveability problems because the crankshaft position signal is essential for engine timing.

Car cranks but will not start

The starter may turn the engine, but the ECU may not trigger fuel or spark correctly.

Engine cuts out

The engine may suddenly stop if the crank signal drops out while driving.

Stalling when hot

Some crank sensors fail when hot and work again after cooling down.

Misfire or rough running

A weak or erratic crank signal can affect ignition and injection timing.

No RPM reading while cranking

A diagnostic tool may show no engine speed signal during cranking.

Engine management light

The warning light may appear with P0335 and related crank/cam signal codes.

Common causes

What causes a P0335 fault code?

P0335 is usually caused by a crank sensor signal problem, but wiring, connectors and mechanical signal targets must also be checked.

Very common

Faulty crankshaft position sensor

The sensor can fail internally, especially with heat, age and vibration.

Wiring

Damaged sensor wiring

Wires can rub through, break, corrode or suffer heat damage near the engine block.

Connector

Corroded or loose connector

Oil, water, road dirt or poor plug fitment can interrupt the crank signal.

Signal issue

Weak or missing RPM signal

The ECU may not see a clean crankshaft speed signal during cranking or running.

Mechanical

Damaged reluctor ring

The sensor reads a toothed or magnetic target. Damage can create missing or inaccurate signals.

Fitment

Incorrect sensor gap

If the sensor is not seated correctly, the signal may be too weak or inconsistent.

Contamination

Oil or metal debris on sensor

Contamination can interfere with the signal, especially on magnetic sensors.

Timing link

Crank and cam correlation issue

Related camshaft codes can appear if crank and cam signals do not agree.

Rare

ECU input fault

Rare, but possible after sensor, wiring, connector and signal checks are completed.

Diagnosis

How a garage should diagnose P0335

✅ Scan all stored, pending and permanent codes.

✅ Record freeze frame data before clearing anything.

✅ Check whether the engine RPM signal appears while cranking.

✅ Inspect the crankshaft sensor connector and wiring.

✅ Check for oil contamination, corrosion or heat damage.

✅ Test sensor power, ground and signal where applicable.

✅ Use live data or oscilloscope testing to confirm signal quality.

✅ Check crank/cam correlation if related camshaft codes are present.

✅ Inspect reluctor ring or trigger wheel if signal remains poor after sensor checks.

Avoid this mistake

Do not replace random starting parts first

If the car cranks but will not start and P0335 is stored, do not jump straight to the battery, starter motor or fuel pump without checking the crank signal. The starter can spin the engine perfectly, but the ECU still may not know where the crankshaft is.

The key clue is live RPM while cranking. If the scanner shows no RPM signal, the crank sensor circuit becomes a very strong suspect.

No-start advice

Can P0335 cause a car to crank but not start?

Yes. P0335 is one of the main fault codes that can cause a crank-no-start problem. The engine may turn over strongly, but the ECU may not trigger ignition or fuel injection correctly because it cannot confirm crankshaft position.

Cranks but no start

The starter works, but the ECU may not see engine speed.

Cuts out when hot

A failing crank sensor can stop working hot and restart after cooling.

No RPM on scanner

No live RPM while cranking is a strong crank signal clue.

Car Cranks But Won't Start Car Won't Start Guide
UK repair cost guide

How much does P0335 cost to fix in the UK?

Costs vary by vehicle, crank sensor access, wiring condition and whether the reluctor ring or timing components need inspection. These are rough UK guide prices only.

Diagnostic scan and live data check

Usually around £40–£120 depending on how much no-start and signal testing is included.

Crankshaft sensor replacement

Can be moderate if access is simple, but some sensors are awkward to reach.

Wiring or connector repair

Cost depends on where the damage is and how much loom access is needed.

Oscilloscope signal testing

May cost more but gives strong evidence for intermittent or weak crank signals.

Reluctor ring inspection

Can become labour-intensive if the trigger wheel is inside the engine or gearbox area.

ECU or advanced diagnosis

Rare, but can be expensive if the sensor and wiring test correctly.

Safe driving advice

Can you drive with a P0335 code?

P0335 should be treated as a serious fault. If the engine cuts out, stalls, loses power, misfires badly or struggles to restart, do not keep driving. A missing crank signal can make the engine stop without warning.

✅ Lower risk: stored code only, car starts normally, no cutting out and no running issue.

⚠️ Medium risk: occasional hard starting, intermittent warning light or rough running.

🚫 High risk: crank-no-start, cutting out, stalling, no RPM signal, severe misfire or sudden power loss.

Real experience

What I would check first

On a real car with P0335, I would check live RPM while cranking before replacing anything. If there is no RPM signal, that points strongly towards the crank sensor circuit.

If the fault happens only when the engine is hot, I would suspect a crank sensor that breaks down with heat. I would also inspect the connector and wiring because oil contamination and heat damage are common around sensor areas.

MOT implications

Will P0335 fail an MOT?

P0335 can lead to an MOT failure if the vehicle has an emissions-related engine warning light, rough running, stalling, misfire, smoke or cannot run properly for the test. If the car cuts out or will not start, it needs repair before being presented for MOT.

Running fault

A car that stalls, misfires or cuts out should be fixed before MOT.

Warning light issue

An engine warning light linked to emissions should be investigated before testing.

No-start problem

If the engine will not start reliably, the vehicle may not be testable.

Engine Light MOT Guide Common MOT Failures
Back to main hub

Browse more OBD fault code guides

P0335 is one common crankshaft position sensor and no-start diagnostic trouble code. For more common codes, meanings, symptoms, repair costs and MOT implications, use the main Motor Vehicle Expert fault-code hub.

Back to OBD Fault Codes Hub Use Diagnostic App
Frequently asked questions

Frequently Asked Questions About P0335

Find answers to common questions about P0335 crankshaft position sensor faults, no-start problems, repair costs and MOT implications.

What does P0335 mean?

P0335 means the engine computer has detected a fault in the crankshaft position sensor circuit. The ECU relies on this signal to know engine speed and crankshaft position.

Can P0335 cause a car not to start?

Yes. P0335 can cause a crank-no-start because the ECU may not know the crankshaft position or engine speed, so it may not control spark or fuel injection correctly.

Can I drive with a P0335 code?

You should be very careful with P0335. If the car cuts out, stalls, cranks but will not start, misfires badly or loses power, avoid driving and get it diagnosed quickly.

Will P0335 fail an MOT?

P0335 can lead to an MOT failure if it causes an emissions-related engine warning light, poor running, stalling, misfire, smoke or the vehicle cannot run properly during the test.

What causes a P0335 code?

Common causes include a faulty crankshaft position sensor, damaged wiring, corroded connector, poor sensor signal, damaged reluctor ring, sensor gap issue, oil contamination or ECU signal problem.

How much does P0335 cost to fix in the UK?

A diagnostic check may cost around £40 to £120. Crankshaft sensor replacement can vary depending on access, while wiring or reluctor ring repairs can cost more if labour-intensive.

About this guide

Based on practical mechanic-style diagnostic experience

Motor Vehicle Expert publishes practical UK vehicle guidance based on real-world mechanical knowledge and hands-on diagnostic experience. This P0335 guide is written to help drivers understand crankshaft position sensor faults before replacing random starting parts unnecessarily.

Fault codes should always be treated as a starting point for diagnosis. If your car cuts out, stalls, cranks but will not start, loses power suddenly or has no RPM signal while cranking, get professional help before continuing to drive.

```