Excell, Your Warranty, and Going Back to Stock
The legal framework, the technical safeguards, and exactly what happens when you unplug the module.
Two of the most common questions we get on the waitlist: 'Will this kill my warranty?' and 'What happens when I want to sell the car?' Both have clear answers.
The Magnuson-Moss Framework
Federal law (Magnuson-Moss Warranty Act, 1975) prevents manufacturers from voiding your entire warranty just because you installed an aftermarket part. They have to prove the part caused the specific failure they're refusing to cover. A starter failure on a car running Excell is still a starter failure.
Why Excell is Specifically Defensible
Excell doesn't reflash your ECU. It doesn't write to any factory memory. It intercepts and modulates two signals — fuel composition and fuel temperature — both of which are designed inputs your ECU was built to receive. From the manufacturer's diagnostic tool perspective, your car looks 100% factory.
Going Back to Stock
Want to sell the car? Trade it in? Hand it down to your kid? Disconnect three plugs and remove the inline fuel hose section. Total time: 12 minutes. Your ECU returns to its factory calibration with zero residual changes — there's nothing to undo because nothing was ever overwritten.
What We Recommend
Save the OEM fuel hose section we replace during install. If you ever revert, swap it back in. With our hardware out, your car is mechanically and electronically identical to the day it left the dealer.