P0315 moderate

Crankshaft Position System Variation Not Learned

The P0315 code means the vehicle's onboard diagnostic system has detected: Crankshaft Position System Variation Not Learned. This is a moderate severity code.

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Keep driving?: Short distances only
DIY difficulty: moderate
Estimated cost: $50 - $300 (parts and labor)

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Common Symptoms

Check Engine Light illuminated
Engine may run rough at idle
Slight hesitation during acceleration
Intermittent misfire codes present
Engine may stall occasionally

Probable Causes (Ranked by Likelihood)

Crankshaft position variation relearn procedure not performed after repair Very High
Faulty crankshaft position sensor High
Damaged or worn reluctor ring on crankshaft Moderate
Excessive crankshaft end play Moderate
PCM software needs update Low

Step-by-Step Diagnostic Procedure

Perform the crankshaft position variation relearn procedure using a scan tool -- follow manufacturer-specific steps
For GM vehicles: warm the engine, apply brakes, then accelerate to the specified RPM until the scan tool confirms relearn
If relearn fails, inspect the crankshaft position sensor for damage, correct air gap, and secure mounting
Check the reluctor ring (tone ring) on the crankshaft for missing or damaged teeth
Verify there is no excessive crankshaft end play using a dial indicator

Frequently Asked Questions

Can I drive with code P0315?

You can drive short distances. The engine should run reasonably well but may have slight drivability issues. The relearn procedure should be performed as soon as possible.

What is a crankshaft position variation relearn?

It is a procedure where the PCM learns the unique characteristics of your crankshaft reluctor ring. This is required after certain repairs like crankshaft sensor replacement, PCM replacement, or engine work.

Is P0315 mainly a GM issue?

Yes. This code is most commonly seen on GM vehicles (Chevrolet, GMC, Cadillac, Buick) that require a specific relearn procedure. Other manufacturers handle crankshaft learning differently.