P0315 Code: Crankshaft Position Variation Learn Procedure Guide

By the CarsDailyHub Editorial Team | Automotive writers; every article fact-checked against OEM service documentation | Updated June 2026

Quick Answer: The P0315 code means “Crankshaft Position Variation Not Learned.” It appears after replacing the crankshaft position sensor when the ECM has not yet learned the new sensor’s position relative to the crankshaft. To fix it, you must perform a Crankshaft Position Variation Learn procedure using a bidirectional scanner (preferred) or a manual throttle procedure (works on some GM and Ford models). Toyota and Honda self-learn automatically. Average cost: $0 (manual) or $80-150 (shop with scanner).

This guide covers the P0315 diagnostic trouble code and the crankshaft position variation learn procedure. Last reviewed: June 2026.

What Does P0315 Mean?
When Does P0315 Appear?
How to Perform the Relearn (Scanner Method)
How to Perform the Relearn (Manual Method)
Which Vehicles Need a Scanner vs Manual?
What Happens If You Ignore P0315?
Why the Relearn Fails (and How to Fix It)
Cost Breakdown: DIY vs Shop
Frequently Asked Questions
Sources & References

What Does P0315 Mean?

P0315 is defined as “Crankshaft Position Variation Not Learned” in the OBD-II standard. It means the engine computer (ECM/PCM) has not stored the reference position of the crankshaft position sensor relative to top dead center (TDC).

Every engine has slight manufacturing variations in the crankshaft reluctor ring (the notched wheel the CKP sensor reads). The relearn procedure teaches the ECM the exact position of these notches on your specific engine. Without this learning, the ECM uses generic default values that may not match, causing timing errors.

The P0315 code is not a sensor failure code. It is a “learning not completed” code. The sensor itself may be working fine. The ECM just has not been told the specific characteristics of the new sensor and crankshaft combination.

When Does P0315 Appear?

P0315 appears in these situations:

After replacing the crankshaft position sensor – The most common trigger. The new sensor has slightly different characteristics than the old one, and the ECM needs to learn the difference.
After replacing the ECM/PCM – A new computer does not have the learned values stored.
After a battery disconnect – On some vehicles, disconnecting the battery for too long erases the learned values.
After engine rebuild – If the crankshaft or reluctor ring was replaced, the ECM needs to relearn.
After clearing codes with a scanner – On some vehicles, clearing all codes also erases the learned crankshaft variation values.

How to Perform the Relearn (Scanner Method)

This is the preferred and most reliable method. You need a bidirectional scan tool that supports “Crankshaft Position Variation Learn” or “CKP System Variation Learn.”

Scanners That Support P0315 Relearn

Scanner	Price	Vehicle Coverage
Autel MaxiCheck MX900	$250-350	GM, Ford, Chrysler
Launch X431 CRP919EBT	$400-500	GM, Ford, Chrysler, some European
Innova 5160RS Pro	$200-300	GM, Ford

See our full guide on what scanner can relearn a crankshaft position sensor for detailed reviews.

Step-by-Step Scanner Relearn

Prerequisites:
– Engine at operating temperature (at least 170°F / 77°C)
– Battery voltage above 12V
– No active misfire codes (P0300-P0306 must be resolved first)
– Transmission in Park or Neutral
– All accessories off (AC, radio, lights)

Steps:

Connect the scanner to the OBD2 port under the dashboard.
Turn the ignition to ON (do not start the engine yet). Wait for the scanner to communicate with the ECM.
Navigate to the relearn function:
– Autel: Diagnostics > Special Functions > Crankshaft Position Variation Learn
– Launch: Diagnostics > Special Functions > CKP System Variation Learn
– Innova: Special Tests > Crankshaft Position Sensor Relearn
Follow the on-screen prompts. The scanner will instruct you to:
– Start the engine
– Confirm engine temperature is above the minimum
– Accelerate to a specified RPM (usually 3,000-4,000 RPM)
– Release the throttle and let the engine return to idle
Wait for confirmation. The scanner displays “Relearn Successful” or similar.
Clear all codes. After a successful relearn, clear the P0315 code and any other stored codes.
Test drive. Drive at varying speeds for 10-15 minutes to confirm the code does not return.

Time: 10-15 minutes. Difficulty: Easy (follow scanner prompts).

How to Perform the Relearn (Manual Method)

This method works on some GM (2000-2010) and Ford (2004-2015) models. It does not work on all vehicles. If it fails, you need a scanner.

GM Manual Relearn

Start the engine and let it reach operating temperature (coolant above 170°F / 77°C).
Turn the engine off and wait 30 seconds.
Restart the engine and let it idle for 2 minutes.
Accelerate to 3,000-4,000 RPM and hold for 5-10 seconds.
Release the throttle completely and let the engine idle for 30 seconds.
Repeat steps 4 and 5 two more times (3 total cycles).
Let the engine idle for 2 minutes.
Turn the engine off and wait 30 seconds.
Restart and test drive for 10-15 minutes at varying speeds.

Ford Manual Relearn

Start the engine and let it reach operating temperature.
Turn the engine off and wait 30 seconds.
Restart and accelerate to 3,000 RPM, hold for 10 seconds.
Release the throttle and let idle for 1 minute.
Repeat steps 3 and 4 two more times.
Turn the engine off and wait 30 seconds.
Restart and test drive for 10-15 minutes.

Alternative Ford Key-Cycle Method

Turn the ignition to ON (do not start).
Depress the accelerator fully and hold for 5 seconds.
Release the accelerator.
Turn the ignition off for 30 seconds.
Start the engine and let it idle for 2 minutes.
Drive at varying speeds for 10 minutes.

If the P0315 code returns after the manual relearn, the manual method does not work on your vehicle. You need a bidirectional scanner.

Which Vehicles Need a Scanner vs Manual?

Make	Manual Relearn Works?	Scanner Required?
GM 2000-2010	Sometimes	If manual fails, yes
GM 2011+	Rarely	Yes, almost always
Ford 2004-2015	Sometimes	If manual fails, yes
Ford 2016+	Rarely	Yes, almost always
Chrysler (all years)	Rarely	Yes, almost always
Toyota	Not needed	Self-learns automatically
Honda	Not needed	Self-learns automatically
Nissan	Rarely needed	Most self-learn
BMW	No	Yes (ISTA required)
Mercedes	No	Yes (XENTRY required)

What Happens If You Ignore P0315?

If you ignore the P0315 code:

Rough idle. The ECM uses default timing values that do not match your crankshaft.
Poor fuel economy. Incorrect timing means inefficient combustion.
Hesitation on acceleration. The ECM may retard timing as a safety measure.
Failed emissions test. P0315 is an active code that will fail most state emissions inspections.
Potential long-term damage. Running with incorrect timing for extended periods can cause carbon buildup and, in severe cases, valve damage.

The vehicle will run, but it will not run correctly. The relearn takes 5-10 minutes with the right scanner or 15 minutes with the manual procedure. Skipping it is not worth the risk.

Why the Relearn Fails (and How to Fix It)

Reason	Fix
Engine not at operating temperature	Warm up to at least 170°F before relearn
Active misfire codes (P0300)	Fix misfire first (spark plugs, coils, fuel)
Battery voltage too low	Charge battery or jump-start before relearn
Throttle did not reach required RPM	Accelerate more firmly to hit target RPM
Faulty replacement sensor	Try OEM or premium brand sensor
Damaged wiring to sensor	Inspect and repair wiring connector
Damaged reluctor ring	Requires engine disassembly to inspect
ECM software bug	Update ECM firmware at dealer

Cost Breakdown: DIY vs Shop

Option	Cost	Time
Manual relearn (GM/Ford)	$0	15-20 min
Buy Autel MaxiCheck MX900 and DIY	$250-350 (one-time)	10 min
Buy Innova 5160RS Pro and DIY	$200-300 (one-time)	10 min
Pay a shop for relearn only	$80-150	15-30 min
Pay a dealer for relearn only	$120-200	15-30 min
Basic OBD2 scanner (cannot do relearn)	$25-40	N/A

Frequently Asked Questions

Q: What does the P0315 code mean?
A: P0315 means “Crankshaft Position Variation Not Learned.” It appears after replacing the crankshaft position sensor when the ECM has not yet learned the new sensor’s position relative to the crankshaft. The sensor may be working fine, but the ECM needs to be taught the specific characteristics of your crankshaft through a relearn procedure.

Q: Can I clear P0315 with a basic OBD2 scanner?
A: You can clear the code, but it will return immediately on the next drive cycle if the relearn has not been performed. A basic $25-40 OBD2 scanner can read and clear codes but cannot perform the relearn. You need a bidirectional scan tool that can send the “Crankshaft Position Variation Learn” command to the ECM.

Q: Can I do the P0315 relearn without a scanner?
A: On some GM (2000-2010) and Ford (2004-2015) models, yes. The manual method involves starting the engine, warming it to operating temperature, accelerating to 3,000-4,000 RPM, holding briefly, releasing, and repeating 3 times. If the P0315 code clears after this procedure, the manual relearn worked. If it returns, you need a bidirectional scanner. Toyota and Honda do not require any relearn at all.

Q: How long does the P0315 relearn take?
A: The scanner-based relearn takes 10-15 minutes including setup. The manual relearn takes 15-20 minutes. At a shop, the entire process including diagnosis takes 15-30 minutes and costs $80-150.

Q: Will P0315 damage my engine if I ignore it?
A: It will not cause immediate damage, but running with incorrect timing for extended periods can cause carbon buildup, poor fuel economy, rough idle, and hesitation. In severe cases, it can cause valve damage. The vehicle will run, but it will not run correctly. You will also fail an emissions test with P0315 active.

Q: Why does the P0315 relearn keep failing?
A: The most common reasons for relearn failure are: engine not at operating temperature, active misfire codes not resolved first, battery voltage too low, throttle not reaching the required RPM, faulty replacement sensor, or damaged wiring. Fix each of these in order before trying the relearn again. If all are addressed and the relearn still fails, the reluctor ring on the crankshaft may be damaged, requiring engine disassembly to inspect.

Sources & References

SAE J2012 – OBD-II Diagnostic Trouble Code definitions (P0315)
GM Service Information – Crankshaft Position Variation Learn procedure
Ford Service Information – CKP System Variation Learn procedure
Autel, Launch, Innova – Scanner product documentation for CPS relearn support
RepairPal – Average repair cost estimates for crankshaft position sensor relearn