Crankshaft Position System Variation Not Learned
The P0315 code indicates that the Engine Control Module (ECM) has not learned the crankshaft position sensor variation, which is necessary for accurate ignition timing and fuel injection. This learning process compensates for manufacturing tolerances in the crankshaft and sensor. The code typically sets after a battery replacement, ECM replacement, or if the relearn procedure was not performed. Without this learned value, the engine may experience misfires, rough idle, or reduced performance.
1. Most Common Causes
- Battery or ECM replacement without performing crankshaft position variation relearn
- Faulty crankshaft position sensor
- Wiring issues in the crankshaft sensor circuit
- ECM software or hardware failure
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine misfire or rough idle
- Hard starting or stalling
- Reduced engine power or hesitation
3. Step-by-Step Diagnosis
Step 1: Scan for codes and verify P0315 is present; check for other related codes.
Step 2: Inspect crankshaft position sensor wiring and connector for damage or corrosion.
Step 3: Perform crankshaft position variation relearn procedure using a scan tool.
Step 4: If relearn fails, test crankshaft position sensor resistance and signal output.
Step 5: Check ECM for software updates or replace if necessary.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the engine may misfire or stall, potentially causing damage to the catalytic converter or other components.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for a relearn procedure at a shop. If sensor replacement is needed, costs can increase to $200-$400.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.