What Is a Crankshaft Position Sensor? CKP Explained [2026]

📖 What It Does

Provides the master timing reference for ignition and fuel injection. Without a CKP signal, the engine simply does not start.

⚙ How It Works

A magnetic or Hall-effect sensor reads teeth on a reluctor ring mounted to the crankshaft or flexplate. The ring has a missing tooth or specific pattern so the ECU can find absolute position. Each pass produces an electrical pulse. Frequency = RPM. Pattern = position.

⚠ Symptoms When It Fails

Classic CKP failure is a hot-soak no-start - the car runs fine cold, dies after warm-up, then restarts when cool. Other symptoms: hard starting, stalling, P0335-P0339 codes, intermittent misfires, and tachometer drops to zero. See full symptom guide.

💰 Replacement Cost

Replacement: $150–$450. Sensor is $25–$150 in parts. Labor varies from 20 minutes (easy access) to 3 hours (deep on the block). See CKP cost.

🔗 Related DTC Codes

❓ Frequently Asked Questions

Why does my car only stall when hot?

Many CKP sensors fail thermally - the magnet weakens or wiring expands open at heat.

How long does a CKP last?

Often 100,000–200,000 miles, but heat-soak failures can come earlier.

Can a bad CKP throw a misfire code?

Yes. Lost signal pulses look like misfires to the ECU.

Will the car start with a bad CKP?

Sometimes yes, sometimes no. Intermittent failure is the classic symptom.

Does the CKP need to be relearned after replacement?

Some vehicles (GM, Chrysler) require a Crank Variation Relearn with a scan tool.

Can I drive with a P0335 code?

Briefly. But sudden stalling on the highway is a real safety risk.

What Is a Crankshaft Position Sensor?