P0335 and P0336 Crank Sensor Codes: A No-Start Diagnosis That Actually Works

A car turns over all day on the starter and won’t fire, no smoke, no sign of life from the injectors. P0335 or P0336 in memory, from the last time it did run, is the giveaway, but neither code on its own tells you if the sensor’s dead, the reluctor wheel’s damaged, or the wiring’s cut somewhere in the harness.

P0335 vs P0336, what’s the actual difference

P0335 is a circuit fault: no signal, an implausible signal, or a circuit malfunction from the crank position sensor. P0336 is a “range/performance” code: the ECU is seeing a signal, but the pattern doesn’t match what it expects, missing teeth appearing at the wrong intervals, or the signal not correlating properly with the camshaft sensor. That difference points you in different directions: P0335 leans towards a wiring or sensor supply fault, P0336 leans towards a mechanical problem with the reluctor wheel or timing.

Diagnostic order for a no-start with this code

1. Confirm sensor supply voltage and earth at the connector with the key on or cranking, most modern crank sensors are Hall-effect and need a clean supply to work at all.
2. Check for a signal at the sensor connector while cranking, using an oscilloscope where possible rather than a multimeter, since a weak or noisy signal often reads “present” on a meter but is unusable to the ECU.
3. Inspect the reluctor wheel for physical damage, broken teeth, corrosion, or a wheel that’s slipped on its keyway, common after a timing belt or chain failure has let something contact the wheel.
4. Check the air gap between sensor and reluctor wheel where it’s adjustable, and check the sensor tip for metal debris that can weaken the signal without killing it outright.
5. Trace the harness for chafing or corrosion, particularly anywhere it runs near the exhaust or has been disturbed by previous work.

Sensor, reluctor or ECU: how to tell them apart

A sensor that’s completely open circuit or shorted usually shows no signal at all on a scope, and that’s a straightforward sensor or wiring fix. A damaged reluctor wheel usually shows an irregular signal pattern, present but wrong, and no amount of sensor swapping fixes that, you need to inspect the wheel itself, which sometimes means removing the timing cover. An ECU input fault is rare but does happen, usually after water ingress or a previous electrical fault elsewhere in the loom; suspect it only once a known-good sensor and a confirmed-good reluctor wheel still produce no usable signal at the ECU pin.

Cross-brand notes

On BMW N47/N57 engines, timing chain wear and guide failure can damage the reluctor pattern indirectly, so a crank sensor code on these engines is worth treating as a possible early warning of chain wear rather than a simple sensor swap. On VAG and PSA units, connector corrosion in the engine bay loom is a frequent cause worth checking before any parts are ordered.

Don’t skip the basics

A discharged or marginal battery can produce a cranking speed too slow for some crank sensors to generate a usable signal, which looks identical to a sensor or wiring fault on a scope until you’ve confirmed cranking speed and battery condition are actually within normal limits. It’s a five-minute check with a load tester and a look at cranking rpm on the scan tool, and it saves hours chasing a sensor or harness fault that was never really there in the first place.

Don’t assume a fresh sensor solves it without confirming the wheel and wiring first, a comeback on a no-start is one of the most expensive kinds because the car often has to be recovered back to you. For more on diagnosing faults that leave a car stuck rather than just showing a light, see the Fault Codes & Diagnostics category, and if the ECU itself needs checking after a failed flash or suspected corruption, recovering a bricked ECU after a failed flash covers the process.