P0335 means the engine computer has lost or can’t reliably read the crankshaft position sensor’s signal — the sensor that tells the ECU exactly where the crankshaft is in its rotation, which is fundamental to timing ignition spark and fuel injection correctly. Because this signal is so basic to engine operation, a complete failure often causes the engine to crank but not start at all, rather than running poorly — see our car cranks but won’t start guide if that’s your exact symptom.
What Does P0335 Mean?
The crankshaft position sensor reads a toothed wheel (the reluctor ring) on the crankshaft to tell the ECU precisely where each cylinder is in its cycle, moment by moment. This is arguably the single most fundamental piece of data the engine computer needs — without it, the ECU cannot correctly time spark or fuel injection, since it has no way of knowing which cylinder needs which action at any given instant.
A complete sensor failure often prevents the engine from starting at all — see our car cranks but won’t start guide — while an intermittent fault can cause sudden stalling while driving, sometimes with no warning at all beyond the code itself once retrieved afterward.
Common Symptoms
- Engine cranks but won’t start — the most common presentation of a complete sensor failure.
- Sudden stalling while driving, with the engine sometimes restarting after a delay and sometimes not, characteristic of an intermittent sensor or wiring fault.
- Rough running or misfiring if the signal is present but degraded rather than completely absent.
- No response at all when attempting to start — no cranking issue, but the engine simply never catches.
Common Causes
- A failed crankshaft position sensor — the component named directly, and the most common cause.
- Damaged, corroded, or disconnected wiring to the sensor, particularly where the harness runs near the exhaust or other heat sources.
- A sensor with excessive air gap from improper installation after a previous repair, or from a damaged reluctor ring on the crankshaft itself.
- Oil contamination on the sensor tip, from a nearby seal leak, interfering with its ability to read the reluctor ring accurately.
- A failed timing belt or chain in rarer, more serious cases, throwing off the relationship the sensor depends on — worth ruling out if the sensor itself tests fine.
How to Diagnose It
- Check for a strong spark and fuel delivery during a no-start, since a healthy crank sensor is required for both — their absence together points strongly at this sensor or its circuit.
- Test the sensor’s resistance and signal with a multimeter or oscilloscope against manufacturer specification.
- Inspect wiring and connectors along the full length of the harness, particularly near heat sources.
- Check for oil contamination at the sensor tip if there’s a nearby seal leak.
Never work under a vehicle supported only by a jack. Use axle stands on firm, level ground, chock the wheels that stay down, and leave the car in gear or Park with the handbrake on. A jack lifts; stands hold.
Possible Fixes
| Cause | Fix | Typical cost |
|---|---|---|
| Failed crankshaft position sensor | Replace the sensor | $100 – $300 |
| Damaged wiring | Repair the affected section | $80 – $250 |
| Oil-contaminated sensor | Clean sensor, fix the leak source | $100 – $400 |
| Timing belt/chain fault | Replace belt/chain and related components | $400 – $1,200 |
Can I Drive With P0335?
Not if the symptom is a no-start or intermittent stalling — this isn’t a fault to drive through, since the engine can cut out with no warning at any moment, which is genuinely dangerous in traffic. If the car is currently running and the code is stored but not actively causing a stall, get it diagnosed immediately rather than waiting, given how fundamental this sensor is to basic engine operation.
When to See a Mechanic
Immediately — this is not a code to postpone, particularly if you’ve experienced even one instance of unexpected stalling. More in our trouble codes section.
Frequently Asked Questions
What does P0335 mean?
The engine computer has lost or can’t reliably read the crankshaft position sensor’s signal — data that’s fundamental to timing ignition spark and fuel injection correctly.
Can P0335 cause a car not to start?
Yes, very commonly — without a reliable crankshaft position signal, the ECU has no way to time spark or fuel delivery, and the engine often cranks without ever actually starting.
Is it dangerous to drive with a P0335 code?
Yes, if it’s causing or has caused stalling — the engine can cut out with no warning at any moment, which is hazardous in traffic. Get it diagnosed immediately rather than continuing to drive.
What causes a crankshaft position sensor to fail?
Most often the sensor itself wearing out, followed by damaged wiring, oil contamination from a nearby seal leak, or excessive air gap from a previous improper installation.
How much does it cost to fix P0335?
Often $100–$300 for a straightforward sensor replacement, more if wiring repair or a timing component turns out to be the actual cause.
