A crankshaft position sensor (CKP) is vital for engine timing and performance. When replacing a CKP sensor, a relearn procedure is often required. This involves using a Crankshaft Position Sensor Scan Tool to communicate with the vehicle’s computer and input new CKP data. This article outlines the crucial steps and prerequisites for a successful CKP relearn procedure using a scan tool.
Understanding CKP Relearn Prerequisites
Before initiating the CKP relearn procedure with your crankshaft position sensor scan tool, ensure your vehicle meets these critical conditions:
Diagnostic Trouble Codes (DTCs)
The following DTCs must not be present. If any of these codes are active, the CKP learn procedure will likely fail:
- P0335 Crankshaft Position (CKP) Sensor A Circuit
- P0336 Crankshaft Position (CKP) Sensor A Performance
- P0341 Camshaft Position (CMP) Sensor Performance Bank 1 Sensor A
- P0342 Camshaft Position (CMP) Sensor Circuit Low Bank 1 Sensor A
- P0343 Camshaft Position (CMP) Sensor Circuit High Bank 1 Sensor A
- P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low
- P0118 Engine Coolant Temperature (ECT) Sensor Circuit High
- P1539 Air Conditioning (A/C) Clutch Feedback Circuit High Voltage
- P1546 Air Conditioning (A/C) Clutch Feedback Circuit Open
- P0705 Transmission Range (TR) Switch Circuit
- P0706 Transmission Range (TR) Switch Performance
- P1810 Transmission Fluid Pressure (TFP) Position Switch Circuit
- P1825 Internal Mode Switch-Invalid Range
Vehicle Conditions
- Engine Coolant Temperature (ECT): Must be between 150°F and 220°F.
- RPM: Must be below 2400 RPM before starting.
- Throttle Position Sensor (TPS): Must read 0%.
- Vehicle Speed Sensor (VSS): Must read 0.
- Parking Brake: Must be engaged.
- Transmission: Must be in Park or Neutral.
- Accessories: All accessories (radio, A/C, etc.) must be off.
- Brake Pedal: Foot must be on the brake pedal.
CKP Relearn Procedure with a Scan Tool
With preconditions met, follow these steps using a compatible crankshaft position sensor scan tool (example using EFILive):
- Connect Scan Tool: Connect the scan tool to the vehicle’s OBD-II port and establish communication.
- Navigate to DVT Tab: Access the “DVT” (Device Variable Table) or equivalent tab within the scan tool software.
- Select Controller: Choose the appropriate engine controller from the list of available modules.
- Activate: Click the “Activate” button to enable the CKP relearn function.
- Learning Subtab: Go to the “Learning” subtab or its equivalent.
- Initiate CASE Relearn: Click the “CASE” (Crankshaft Angle Sensor Error) relearn button.
- Increase RPM: Quickly open the throttle to increase engine RPM above 4000 within 10 seconds.
- Release Throttle: As soon as the engine stumbles or misfires, immediately release the throttle.
- Engine Idle: Allow the engine to return to idle speed.
- Turn Off Engine: After reaching idle, turn off the engine and wait for 15 seconds.
- Deactivate: While waiting, you can click “Deactivate” within the scan tool software.
Conclusion
Using a crankshaft position sensor scan tool is crucial for successfully performing a CKP relearn. Following the correct procedure and ensuring all prerequisites are met will help ensure accurate engine timing and optimal performance. If you encounter difficulties, consult your vehicle’s service manual or a qualified automotive technician.
