Method for OTA updating vehicle electronic control unit

A method for updating a vehicular electronic control unit (ECU) comprising a flash memory storing a digital content image and a boot loader is provided. The method comprises: generating a differential update package (DUP) for said ECU to update the digital content image to an updated digital content image, said DUP comprising instructions to perform one or more of copying bytes from said flash memory, and applying a set of modifications to said copied bytes; transmitting said DUP over a wireless carrier system to a telematics device of the vehicle; storing an original block portion of said digital content image; modifying said original block portion in accordance with said DUP to produce a modified block portion; erasing said original block portion from said flash memory; and writing said modified block portion into said flash memory in place of said original block portion.