P0335 Code: Crankshaft Position Sensor Circuit Malfunction

What the code actually means#

SAE J2012 defines P0335 as "Crankshaft Position Sensor 'A' Circuit Malfunction". The CKP sensor reads a toothed reluctor wheel on the crankshaft (or harmonic balancer) and sends the PCM a pulse train. The PCM uses these pulses for ignition timing, fuel injection timing, misfire detection, and engine speed.

When the PCM sees no signal during cranking, an intermittent dropout above a certain rpm, or a signal pattern that does not match the expected tooth count, P0335 sets. Related siblings:

• P0336: Range/performance — signal present but unrealistic.
• P0337: Signal low.
• P0338: Signal high.
• P0339: Signal intermittent.

P0335 is a one-trip code. On many vehicles, the engine cannot start without a CKP signal at all — the PCM will not pulse the injectors.

Symptoms#

• Check engine light on (when the engine runs).
• No-start, even with strong cranking and good fuel pressure.
• Engine stalls without warning, then restarts after a 5–10 minute cool-down.
• Intermittent misfire under load.
• Tachometer drops to zero or twitches randomly.
• Hard hot-start that improves once the engine cools.

The hot-stall pattern — runs fine cold, stalls at operating temperature, restarts after cooling — is the signature failure mode of an aging CKP sensor.

Is it safe to drive?#

No, not regularly. A CKP fault can stall the engine at speed without warning. Power steering boost cuts, brake assist cuts after one or two pumps, and ignition switches to ACC. On a highway, that is a serious hazard.

Limit driving to short trips at low speed until the sensor is diagnosed and repaired. If the vehicle won't start at all, you are safer — repair first, drive later.

What causes it — most common first#

1. Failed CKP sensor (~70%). The internal magnet weakens with age and heat. Signal works cold but dropouts begin once the sensor reaches operating temperature. Clue: hot-stall pattern; signal returns after the engine cools for 10–15 minutes.

2. Damaged sensor connector or wiring (~15%). Heat near the exhaust manifold (where many CKP sensors sit) cooks the pigtail. Clue: visible discoloration on the connector or wire insulation; wiggle test at idle changes the signal on a scope.

3. CKP sensor mounting clearance issue (~5%). Sensor air gap to the reluctor is out of spec — usually after a sensor replacement with the wrong mounting bracket. Clue: code returned within days of a CKP replacement.

4. Reluctor ring damaged or contaminated (~5%). Metal shavings from a previous oil-pump or harmonic-balancer failure clinging to the reluctor teeth. Clue: recent major engine work; chunks missing from the tone wheel visible on inspection.

5. PCM driver fault (~3%). Internal driver in the PCM that reads CKP has failed. Clue: sensor and wiring test good, signal still absent at the PCM.

6. Faulty crankshaft sensor harmonic damper (~2%). Outer ring of the harmonic balancer has shifted relative to the inner hub, throwing off the tone-wheel position. Clue: timing-mark verification with a timing light shows wandering ignition timing.

How to diagnose it, in order#

1. Verify the no-start versus run-with-fault pattern#

A vehicle that cranks but won't start almost certainly has no CKP signal at all. A vehicle that runs but throws the code intermittently has a marginal signal. The diagnostic path differs.

2. Read freeze-frame data#

Note coolant temperature and rpm when the code set. Code set at high coolant temp and zero rpm = sensor dropped out at operating temp, classic aging sensor.

3. Check the CKP connector and wiring#

With the engine off and key out, inspect the CKP connector for:

• Corrosion on the pins.
• Heat damage to the plastic shell.
• Broken or pinched wires.

Repair any visible damage and recheck. About 15% of P0335 codes clear here.

4. Test sensor resistance (passive 2-wire sensors)#

A magnetic reluctor sensor has a specific resistance spec (typically 500–1,500 ohms). Measure with a DVOM at the sensor connector; out-of- range readings confirm a failed sensor.

Active 3-wire Hall-effect sensors require a different test — see factory service manual for voltage and signal waveform spec.

5. Scope the signal at crank#

A handheld oscilloscope (or a scan-tool live-data graph) at the CKP signal wire while cranking shows the pulse train. Missing or distorted pulses confirm the failure. Continuous clean pulses point at the connector or PCM.

6. Verify reluctor ring after major engine work#

If the code appeared after a timing-belt, harmonic-balancer, or oil-pump repair, pull the cover and inspect the reluctor for damage or debris.

Fixes, cheapest first#

A CKP sensor replacement is 30–90 minutes on most inline-4 engines (sensor accessible at the rear of the block or on the timing cover). On some V6 engines (especially the GM 3.6L), the CKP sits behind the intake manifold and the job runs 3–5 hours.

How to reset the code after a repair#

Clear with a scan tool, then drive a mix of city and highway through one full warm-up cycle. The CKP monitor runs continuously while the engine spins, so the code either clears within the first 5 minutes or returns to confirm.

What to do if it comes back#

• Within a week of replacing the sensor: new sensor may be defective (common with budget aftermarket) or mounting bracket is off-spec. Use OEM for CKP sensors when possible.
• After driving through a puddle or heavy rain: water in the CKP connector. Replace the pigtail and apply dielectric grease.
• No change after sensor and wiring replaced: scope the signal at the PCM connector. If the signal is clean at the sensor but missing at the PCM, the wiring between has an open circuit or the PCM driver has failed.

Related OBD-II codes#

Frequently asked questions#