Crankshaft Position Sensor 'A' Circuit Malfunction

The crank position sensor (CKP) tells the PCM where the crankshaft is and how fast it's spinning. Without it, the PCM doesn't know when to fire spark or pulse injectors — the engine won't start, or will stall once it gets warm. P0335 sets when the signal is missing, intermittent, or out of pattern with the cam sensor. Classic symptom: starts fine cold, stalls when hot, then won't restart until it cools. That's a heat-sensitive crank sensor every time. Also very common: cracked reluctor wheel, debris on the sensor tip, or a wiring rub.

No pulses from the CKP during cranking, or pulse count doesn't match expected pattern for the reluctor wheel. May also flag if CKP and CMP signals don't correlate.

Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.

1. 1Confirm the complaint. Crank-no-start with no RPM signal on the scan tool during cranking = textbook P0335.
2. 2Hot-stall complaint? Heat-soak the sensor with a heat gun (not torch) and watch the signal die. Sensor is condemned.
3. 3Pull the sensor and inspect the tip. Metal shavings stuck to a magnetic-style sensor will kill the signal. Clean and reinstall before condemning.
4. 4Scope the sensor during cranking. VR sensor wants a clean AC waveform, amplitude rising with RPM. Hall wants a crisp 0–5 V square wave. Dropouts in the pattern = bad reluctor wheel.
5. 5Check sensor resistance (VR type) against spec — usually 500–1500 Ω. Open or shorted = replace.
6. 6Inspect the wiring from sensor to PCM. Look for chafe points where the harness passes near the head, exhaust, or A/C lines.
7. 7If sensor and wiring check good and signal is still missing, scope the signal at the PCM connector. If it's there at the PCM but not being processed — then suspect the PCM.

• Heat-soaked CKP sensor that quits when hot (#1 cause)
• Cracked or damaged reluctor wheel / tone ring
• Metal debris stuck to magnetic sensor tip
• Chafed / broken sensor wiring near harness routing points
• Failed sensor outright (no signal cold either)
• PCM-side issue (rare — confirm sensor first)

CKP sensor $30–$200. Labor $80–$400 depending on access. Reluctor/flexplate ring $400–$1,500 (transmission usually has to come out).