Crankshaft variation learning procedure was never performed after a repair or battery replacement; Engine computer (PCM) replaced or reflashed without completing the relearn; Crankshaft position sensor replaced without performing the variation learn; Weak or failing crankshaft position sensor producing an inconsistent signal; Wiring damage or poor connection at the crankshaft position sensor; Reluctor wheel damage or debris on the crankshaft trigger wheel; Low battery voltage or interrupted power during a previous learn attempt

DTC codes / P03xx · Ignition system and misfire / P0315

P0315Crankshaft Position System Variation Not Learned

Q: What does code P0315 mean?

Crankshaft Position System Variation Not Learned. P0315 means the engine computer has not learned the small manufacturing tolerances in the crankshaft position sensor signal, so it cannot reliably detect misfires. The computer stores this code when the crankshaft variation learning procedure has never been completed or the learned values have been erased.

P0315 means the engine computer has not learned the small manufacturing tolerances in the crankshaft position sensor signal, so it cannot reliably detect misfires. The computer stores this code when the crankshaft variation learning procedure has never been completed or the learned values have been erased.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Rough running or misfire feeling if the unlearned variation affects misfire detection
Slightly reduced fuel economy in some cases
Intermittent stalling or hard starting if the crank sensor signal is erratic
Failed emissions test due to the check engine light being on

Common causes, most likely first

Crankshaft variation learning procedure was never performed after a repair or battery replacement
Engine computer (PCM) replaced or reflashed without completing the relearn
Crankshaft position sensor replaced without performing the variation learn
Weak or failing crankshaft position sensor producing an inconsistent signal
Wiring damage or poor connection at the crankshaft position sensor
Reluctor wheel damage or debris on the crankshaft trigger wheel
Low battery voltage or interrupted power during a previous learn attempt

How to diagnose and fix it

Verify battery voltage is stable and fully charged before any relearn attempt
Inspect the crankshaft position sensor and its wiring for damage or corrosion
Check for any other stored codes, especially crank sensor circuit codes, and repair those first
Use a scan tool to perform the crankshaft position system variation learn procedure
Confirm the learn completed successfully by clearing codes and test-driving
If the learn fails repeatedly, check the reluctor wheel for damage or debris
Replace the crankshaft position sensor only after electrical checks and a failed relearn

Why the crank variation learn fails

Many technicians replace the crankshaft sensor when the real problem is simply that the variation learn was never performed after a previous repair.
A weak battery or poor ground can cause the learn procedure to abort silently, leaving the code stored even though all hardware is fine.
The code does not always mean the sensor is bad; it often appears after a PCM replacement or software update that wipes the learned values.
Some vehicles require the engine to be at full operating temperature and all accessories off during the learn, or the procedure will not complete.
If the reluctor wheel has a chipped tooth or metal debris stuck to it, the learn will fail every time until the wheel is cleaned or replaced.

Can I keep driving with P0315?

You can usually drive the vehicle, but the computer may not detect misfires properly, which can damage the catalytic converter over time. Avoid heavy acceleration or towing until the variation learn is completed and the light is off.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.