The P0315: Crankshaft Position System Variation Not Learned code means that the vehicle’s computer (PCM) has not learned the variation of the crankshaft position, which is necessary for accurate engine timing and operation. This learning process can be disrupted by sensor issues, component replacements, or electrical problems.
P0315 quick overview
| Meaning | P0315: Crankshaft Position System Variation Not Learned |
| Is it serious? | This code is quite serious as it can affect the vehicle’s performance and fuel efficiency, potentially leading to further engine problems if not addressed. |
| Possible causes | – Faulty crankshaft position sensor – Incorrectly installed crankshaft or camshaft sensor – Wiring issues between the crankshaft position sensor and PCM – Newly installed engine or components not calibrated – Faulty PCM |
| How to diagnose? | Check Sensor Installation: Verify that the crankshaft and camshaft sensors are correctly installed. Inspect Wiring and Connectors: Look for damaged wiring or loose connectors between the sensors and the PCM. Perform Relearn Procedure: Use a diagnostic scanner to attempt the crankshaft position system variation relearn procedure. Clear Codes Before Relearn: Ensure all existing codes are cleared before attempting the relearn. Verify Battery Health: Make sure the vehicle’s battery is fully charged. Review PCM and BCM Programming: Confirm that any recently replaced PCM or BCM is correctly programmed. Address Related DTCs: Resolve any other diagnostic trouble codes that may prevent successful relearning. |
P0315 Meaning
When you see the P0315 code, it tells you that the car’s computer can’t properly track the engine’s speed and position. This is like trying to ride a bike with your eyes closed – you can keep going for a bit, but eventually, you’ll run into trouble. The computer needs to “learn” how the engine moves to manage it effectively, and something is preventing this from happening. Fixing it might involve checking sensors, wires, or even reprogramming the car’s computer. It’s important to get this sorted out to keep your car running smoothly and avoid more significant issues down the line.
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How to fix P0315 – learn from mechanics
I looked into P0315 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.
Case #1: Chevrolet
Vehicle Information: 2003 Chevrolet Suburban 1500 LS 5.3L
Issue + Repair History:
- MIL on with code P0315 after PCM replacement.
- Original issue was no cluster function with codes U1000, U1016 indicating no communication with PCM.
- Replaced and programmed PCM; cluster function and communication restored.
- Unable to perform crankshaft variation relearn; RPM exceeded cut point during procedure.
Suggestions to Fix Issue:
- Ensure engine is at operating temperature before attempting relearn.
- Follow the relearn procedure instructions exactly without anticipation.
- Check for any misfires and ensure coolant temperature is correct for the relearn procedure.
- Look into a Technical Service Bulletin (TSB) for an updated crankshaft position (CKP) sensor.
Final Fix:
- After clearing the code and test driving the vehicle, the technician was able to successfully perform the crankshaft variation relearn procedure, resolving the P0315 issue.
Case #2: Ford
Vehicle Information: 2012 Ford F-150 King Ranch 5.0L
Issue + Repair History:
- Came in with P0315 code.
- Attempted misfire relearn, but code returned.
- Replaced crank sensor, leading to a no-start issue.
- New sensor tested and passed, but no cam-crank sync in live data.
- Fuel cranking disabled.
- Checked wires from PCM to crank sensor; good continuity.
- Replaced pigtail for crank sensor without resolution.
Suggestions to Fix Issue:
- Suspect wiring to the CKP sensor.
- Suggested checking connector and wires close to the connector terminals for breakage.
- Ensure crank/cam sync for fuel/crank signals to be enabled by PCM.
- Questioned if an OEM (FMC) sensor was used, noting aftermarket can be unreliable.
- Suggested trying a battery disconnect for electronic issues.
- Emphasized understanding code set criteria, hinting at PCM issue.
Final Fix:
- Replacing the PCM solved all issues.
Case #3: Chevrolet
Vehicle Information: 2006 Chevrolet Corvette Z06 7.0L
Issue + Repair History:
- Replaced ECM and received a failure to calibrate camshaft sensor code (315).
- Replacement of crank sensor did not resolve the issue; vehicle failed to start.
- Live data showed fuel cranking disabled and no cam-crank sync.
Suggestions to Fix Issue:
- Start and run the Corvette 2-3 times for self-calibration if it starts.
- Turn power off to ECM for 30 seconds if it does not start, then reinstall the sensor for it to default to original ECM settings.
- Ensure no breakage in wires close to the connector terminals.
- Check for cam/crank sync for fuel/crank signals to be enabled by PCM.
- Consider whether the ECM programmer is aware of the calibration process.
- Use a Tech 2 for crank learn procedure.
Final Fix:
- Realized the correct procedure to hold the brake from the clutch once starting the engine, allowing the calibration to complete successfully.
Case #4: Dodge
Vehicle Information: 2008 Dodge Grand Caravan SXT 3.8L
Issue + Repair History:
- Came in with MIL on and P0315 code (crank sensor not learned) from another shop, unable to pass emissions.
- Replaced crankshaft sensor, camshaft sensors, timing chain, PCM (new and used), and flexplate.
- Overlaid cam and crank circuits but still had P0315 with no drivability issues.
- MIL reactivates after test driving with the same P0315 code.
Suggestions to Fix Issue:
- Perform decel events required for crankshaft tone wheel learning.
- Check for potential memory resets or keep alive memory input loss on the PCM.
- Compare synch shot waveforms with reference archives for cam and crank alignment.
- Review parameters and conditions for crank position learning, including checking other sensor inputs like ECT for out-of-range but non-code-setting values.
Final Fix:
- After comparing the aftermarket flexplate with an OEM one, discovered the crank and cam were not in sync due to the aftermarket flexplate. Replacing it with an OEM flexplate resolved the P0315 issue.
Case #5: Pontiac
Vehicle Information: 2007 Pontiac G5 2.2L
Issue + Repair History:
- Customer replaced BCM with a used unit for a shift lock issue, which did not resolve the problem. Original BCM was reinstalled.
- MIL on with codes P0315 (Crank Variation Not Learned) and U0121 (Lost Communication With EBCM), despite the vehicle not having ABS/TCS.
- Replaced PCM with a used unit and programmed it, but the same DTCs persisted.
- Crank Variation Relearn could not be completed, exiting with DTC current/fault exists.
Suggestions to Fix Issue:
- Check brake pedal switch input on the scan tool for issues affecting CKP relearn and BTSI concern.
- Clear the code just before performing the crank relearn.
- Ensure the battery is fully charged during relearn and all codes are cleared prior.
- Inspect BCM pins for any bent.
Final Fix:
- Resolved the original shift interlock problem by diagnosing a missing ground circuit to the range switch, caused by corroded and separated grounds from the copper eyelet attached to the transmission.
- After repairing the ground, the transmission range switch logic matched the chart, the shift interlock functioned properly, and the Crank Variation Relearn was successfully completed, clearing the MIL.
- U0121 DTC remained as an erroneous code that could not be cleared.
How to diagnose P0315
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Advice | Brief Description of Diagnostic Step |
|---|---|
| Perform Crank Variation Relearn | Use a diagnostic scanner to run through the crankshaft position sensor relearn procedure. |
| Check for related DTCs | Prioritize resolving any related diagnostic trouble codes that might prevent the relearn from completing. |
| Inspect wiring and connections | Examine wiring for the crankshaft and camshaft sensors, as well as the BCM and PCM, for damages or loose connections. |
| Ensure proper vehicle conditions for relearn | Verify that the engine is at operating temperature and all prerequisites for the relearn are met. |
| Clear codes before relearn | Attempt to clear any existing fault codes before performing the relearn procedure. |
| Check battery health | Make sure the vehicle’s battery is fully charged to avoid any issues during the diagnostic process. |
| Inspect sensor installation and condition | Ensure that the crankshaft and camshaft sensors are correctly installed and in good condition. |
| Review PCM and BCM programming | Verify that the PCM and BCM are correctly programmed, especially after replacement or reinstallation. |
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko