P0335

What P0335 means

The crankshaft position sensor tells the computer exactly where the crankshaft is and how fast it's spinning. The engine computer uses that signal to time the spark and the fuel injectors. P0335 means the computer isn't getting a clean, believable signal from that sensor. It doesn't necessarily mean the sensor itself is bad. It means the signal coming from that circuit doesn't make sense, and it could be the sensor, the wiring, the connector, or something mechanical throwing off the signal.

Is it safe to drive

Treat this one seriously. A crankshaft position sensor problem can cause the engine to stall without warning, run rough, or simply not restart once it's shut off. Some cars will limp along fine for a while and then die suddenly, often at the worst possible moment, like in an intersection. If the check engine light is flashing, or the engine has already stalled or is stalling intermittently, don't keep driving it. Have it towed or diagnosed before you put more miles on it. If the light is steady and the car is running normally, it's less urgent, but don't ignore it and don't put off getting it looked at.

Common causes, roughly in order

Wiring and connector problems are very common with this code — a corroded pin, a chafed wire, or a connector that's not seated fully. The sensor itself failing is next, either from heat, age, or oil contamination on models where it sits near an oil leak. Sometimes the issue isn't the sensor or wiring at all but the sensor's mounting or air gap being off after other work was done nearby. On some engines a worn timing chain, stretched belt, or a damaged reluctor/tone ring (the toothed wheel the sensor reads) can also cause this code, and that's a bigger job. Which of these is likely depends a lot on the engine — some engines are known for sensor failures, others are known for wiring chafe points, so there isn't one universal answer.

What diagnosis involves and what it tends to cost

Diagnosis means checking the sensor's wiring and connector, testing the sensor's actual output signal with a scope or meter rather than just swapping it, and checking the related mechanical parts if the wiring and sensor test out fine. Just replacing the sensor without that testing is how people end up paying twice. Rough costs: diagnostic time is usually a separate charge from any repair. If it turns out to be the sensor itself, parts and labor together are commonly in the low hundreds of dollars, depending on the vehicle and how accessible the sensor is — some are a ten-minute job, others require a lot of disassembly. If it's a wiring repair, cost depends on where the damage is. If it turns out to involve the timing chain or tone ring, that's a larger job and cost. We won't know which one it is until it's tested.