P0315
System
Powertrain (Engine)
Scanner required
Full-system scanner (engine, ABS, SRS, transmission, service resets)

Crankshaft Position System Variation Not Learned

Understand P0315, common causes, and the right TOPDON scanner to diagnose it.

PCM has not learned crankshaft position variation — required after crank sensor, PCM, or harmonic balancer service on many GM/Ford models.

Common symptoms

  • Rough idle after repair
  • Misfire codes
  • Stalling
  • No-start after battery disconnect on some models

Typical causes

  • Crank relearn not performed after repair
  • New crank sensor without relearn
  • PCM replacement
  • Damaged reluctor ring

What scanner do you need?

Full-system scanner (engine, ABS, SRS, transmission, service resets)

Use live data and freeze frame to confirm the fault before replacing parts. ABS, SRS, and network U-codes usually require a full-system scanner.

Diagnostic tips

  • Record freeze frame data when the code first sets
  • Clear the code only after fixing the root cause
  • Check for related pending codes that point to a common issue
  • Verify battery voltage is above 12.4V before chasing sensor codes

Recommended TOPDON scanners

Frequently asked questions

Can I diagnose P0315 with a basic code reader?
P0315 may set in the engine module, but related diagnostics often benefit from an enhanced or full-system scanner with live data and freeze frame.
Is it safe to drive with P0315?
It depends on the code and symptoms. Flashing check engine lights and misfire codes should be addressed immediately. Consult a professional if unsure.