What Does P0315 Mean?
The crankshaft position system variation has not been learned by the PCM. This procedure teaches the PCM the unique machining tolerances of the crankshaft reluctor wheel so it can accurately detect misfires. Without this learned variation, the misfire detection system cannot function properly, and the driver may notice false misfire codes or a persistent check engine light after certain repairs.
Common Causes
40%
CKP variation learn procedure not performed after crankshaft sensor, engine, or PCM replacement
25%
PCM memory was cleared (battery disconnect or reflash) and variation values were lost
15%
Faulty crankshaft position sensor providing inconsistent signal preventing successful learn
12%
Damaged or worn crankshaft reluctor wheel with chipped or missing teeth
8%
Excessive crankshaft endplay or bearing wear affecting sensor-to-reluctor gap
Diagnostic Steps
1
Attempt the CKP variation learn procedure using the scan tool: bring engine to operating temperature, then accelerate from idle to the specified fuel cutoff RPM (typically 4,000–5,150 RPM depending on application) and release the throttle quickly — repeat until the tool confirms learned.
2
If the learn procedure fails, check the CKP sensor wiring for proper resistance (typically 500–900 ohms for magnetic type) and inspect the connector for corrosion or bent pins.
3
Use an oscilloscope to verify the CKP signal waveform during cranking — look for consistent amplitude and no missing teeth patterns beyond the designed gap.
4
Inspect the crankshaft reluctor ring/tone wheel for physical damage, cracks, or debris on the teeth that could cause signal irregularities.
5
Verify the CKP sensor air gap is within specification (typically 0.5–1.5mm) and that the sensor is properly torqued to the mounting boss.
Estimated Repair Cost
$50 - $350
Parts + labor, varies by vehicle and location
The crankshaft position system variation has not been learned by the PCM. This procedure teaches the PCM the unique machining tolerances of the crankshaft reluctor wheel so it can accurately detect misfires. Without this learned variation, the misfire detection system cannot function properly, and t...
The most common cause of P0315 (Crankshaft Position System Variation Not Learned) is: CKP variation learn procedure not performed after crankshaft sensor, engine, or PCM replacement
Typical repair costs for P0315 range from $50 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle is generally safe to drive, but the misfire detection system will not function correctly, meaning actual misfires may go undetected. This could mask cylinder misfires that might damage the catalytic converter. Have the learn procedure performed at the next convenient opportunity.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0315 to identify the root cause.
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Quick Info
Category
Powertrain
System
Ignition / Engine Management
Difficulty
Type
Generic (SAE)
Recommended Tools
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