P0315 Code: Causes, Symptoms, Diagnosis & How to Fix It
P0315 means “Crankshaft Position System Variation Not Learned.” It is a generic OBD2 powertrain trouble code related to the relationship between the crankshaft position sensor and the engine control module.
The PCM/ECM uses crankshaft position information to understand the engine's rotational position and variation. On many vehicles, a crankshaft position variation relearn is required so the computer can accurately interpret these variations for engine operation and misfire detection.
P0315 can appear when the relearn procedure has not been performed correctly, has failed, or when a problem with the crankshaft sensor, wiring, timing components, or reluctor/tone wheel prevents the system from learning the required values.
The exact procedure and conditions for a crankshaft variation relearn vary by manufacturer, so vehicle-specific service information should always be followed.
P0315 Code Symptoms
Common symptoms of P0315 may include:
Check Engine Light
Engine misfire
Engine bucking or surging
Hesitation during acceleration
Engine stalling
Hard starting
Crank-no-start condition
Rough engine operation
Reduced engine performance
Some vehicles may run normally even though P0315 is stored, while others may experience starting or drivability problems.
Common Causes of P0315
Several conditions can trigger a
1. Crankshaft Variation Relearn Was Not Performed
This is one of the most common causes. The relearn may be required after certain engine or crankshaft-related repairs.
2. Crankshaft Position Sensor Problem
A faulty, damaged, incorrectly installed, or incompatible crankshaft position sensor can provide inaccurate position information.
3. Damaged Sensor Wiring or Connector
An open circuit, damaged wire, corrosion, loose terminal, or poor electrical connection can interfere with the crankshaft sensor signal.
4. Damaged Reluctor or Tone Wheel
The reluctor, tone ring, flexplate, or other crankshaft reference component can become damaged or distorted and produce an incorrect position signal.
5. Worn Timing Components
Excessive timing-chain slack or worn timing components can affect the relationship between crankshaft position and engine timing.
6. Mechanical Crankshaft Problems
Crankshaft-related mechanical variation or damage can prevent the PCM from successfully learning the required position values.
7. PCM or Software Problem
A PCM failure or calibration/software issue is less common but can contribute to P0315 after other potential causes have been eliminated.
When Can P0315 Appear?
P0315 may appear after work involving components that affect crankshaft position information.
Examples include:
Replacing the crankshaft position sensor
Engine replacement
Crankshaft replacement
Certain timing repairs
PCM replacement or programming
Other engine repairs requiring a crankshaft variation relearn
Not every vehicle requires the same relearn procedure after every repair. Always check the manufacturer's service information for the specific vehicle.
How to Diagnose P0315
The goal is to determine whether the problem is simply a missing relearn or whether an underlying mechanical or electrical fault is preventing the relearn from completing.
Step 1: Scan for All Trouble Codes
Use an OBD2 scanner to retrieve stored and pending codes.
Record freeze-frame information and check for other crankshaft, camshaft, ignition, misfire, or communication codes.
Step 2: Check the Vehicle's Repair History
Determine whether the crankshaft position sensor, engine, timing components, crankshaft, or PCM was recently replaced.
If recent work was performed, verify whether a crankshaft variation relearn was required.
Step 3: Inspect the CKP Sensor and Wiring
Locate the crankshaft position sensor and inspect its connector and wiring.
Look for:
Damaged insulation
Chafed wires
Corrosion
Loose terminals
Burned wiring
Oil contamination
Poor connector engagement
Repair any confirmed wiring or connection problems before attempting another relearn.
Step 4: Check the Crankshaft Sensor Signal
Use the appropriate scan-tool data or diagnostic equipment to verify that the crankshaft position sensor is producing a consistent signal.
An intermittent or inaccurate signal can prevent the PCM from learning crankshaft variation correctly.
Step 5: Inspect Timing Components
If the electrical system checks out, inspect the mechanical timing system.
Excessive timing-chain slack, damaged timing components, or incorrect mechanical timing can interfere with the crankshaft position signal.
Step 6: Inspect the Reluctor or Tone Wheel
Check the relevant crankshaft reference component for damaged, missing, cracked, or distorted teeth or reference points.
Mechanical damage in this area can create an inaccurate crankshaft position signal.
Step 7: Perform the Crankshaft Position Variation Relearn
If the vehicle and scan tool support the procedure, perform the manufacturer-specified crankshaft position variation relearn.
The exact operating conditions vary by vehicle. Some procedures require specific engine temperature, RPM, transmission position, or other conditions.
Do not use a generic relearn procedure without confirming that it applies to the vehicle being serviced.
Step 8: Clear Codes and Retest
After completing the repair or successful relearn, clear the diagnostic codes and test the vehicle.
Confirm that P0315 does not return and that the engine starts and runs normally.
How to Fix P0315
The correct repair depends on what caused the code. Possible repairs include:
Perform the required crankshaft position variation relearn
Replace a faulty crankshaft position sensor
Repair damaged CKP sensor wiring
Repair corroded or loose electrical connections
Correct mechanical timing problems
Repair or replace a damaged reluctor or tone wheel
Repair damaged timing components
Address PCM programming or calibration issues when manufacturer information identifies them
Replace the PCM only after proper diagnosis confirms it has failed
A crankshaft relearn may be required after certain sensor or engine repairs. AutoZone also notes that some vehicles, particularly certain GM models, require a crank relearn after relevant camshaft or crankshaft sensor replacement.
Is P0315 Serious? Can You Drive With It?
P0315 should be diagnosed rather than ignored.
If the engine starts and runs normally with only a steady Check Engine Light, a short trip to a repair facility may be possible.
However, avoid driving if the vehicle:
Stalls repeatedly
Has severe misfires
Has major power loss
Is difficult to start
Cranks without starting
Has a flashing Check Engine Light
A crankshaft-position problem can affect engine starting and drivability, and some vehicles may crank without running when the condition is severe.
P0315 vs P0335
P0315 means the crankshaft position system variation has not been learned.
P0335 generally indicates a crankshaft position sensor A circuit malfunction.
The two codes can involve the same general sensor system, but they point toward different diagnostic directions. P0315 focuses on the learned crankshaft variation, while P0335 focuses on a sensor circuit fault.
P0315 vs P0300
P0315 relates to crankshaft position variation learning.
P0300 means Random/Multiple Cylinder Misfire Detected.
A P0315 problem can contribute to misfire-related symptoms because accurate crankshaft position information is important to engine control and misfire detection.
Frequently Asked Questions
What does P0315 mean?
P0315 means Crankshaft Position System Variation Not Learned.
Does replacing a crankshaft sensor require a relearn?
On some vehicles, yes. The exact requirement depends on the manufacturer and vehicle. Always check the service procedure for the specific model.
Can a bad crankshaft position sensor cause P0315?
Yes. A faulty or incorrectly functioning crankshaft position sensor can prevent the PCM from learning the required crankshaft variation.
Can P0315 cause a no-start?
It can contribute to starting problems on some vehicles. Depending on the vehicle and the underlying fault, the engine may crank without starting.
Can low battery voltage cause P0315?
Low or unstable electrical power can interfere with diagnostic procedures and module operation. Before performing a relearn, make sure the vehicle meets the manufacturer's required electrical and operating conditions.
Can timing problems cause P0315?
Yes. Worn or incorrectly timed components can affect the relationship between crankshaft position and engine timing and may prevent a successful relearn.
