Service function guideIdle Relearn Procedure

This guide covers the complete idle relearn procedure for restoring a stable, factory-specified idle after a battery replacement, throttle body service, or sensor change on modern electronic throttle control systems. It is written for working mechanics and experienced DIY owners who already understand basic engine management and scan tool operation. You will learn how the engine control module (ECM) learns idle trim, how to prepare the vehicle and shop environment, and how to execute the relearn sequence across common vehicle architectures. By the end, you will be able to verify a successful relearn with scan data and road-test behavior, diagnose a failed relearn, and apply the correct aftercare so the idle remains stable.