EFI-equipped vehicles like the Land Rover Defender 2.4L rely on integrated Engine Control Modules (ECM) and immobilizers for optimal performance and security. However, high OEM procurement costs have made maintenance both expensive and timeconsuming. To address this challenge, a detailed teardown and fault analysis of the ECM and immobilizer was conducted. This led to the successful development and implementation of an in-house programming and repair solution, eliminating dependency on OEM sources and enabling rapid, cost-effective restoration