Disconnect the cables from the servo and re-fit it. It will still operate and the ECU thinks it’s working as usual but all it’s doing is turning its motor. An alternative is to replace the servo with a servo buddy. Both solutions keep the engine management light out.
Skutrnet sells them for about $65 here. Woodcraft as well, but it is just a re-labeled Skutrnet piece. I have one on mine, works great. https://www.skutr.net/
I did this on mine and it worked a treat , then a servo buddy come up on here at a decent price so I got it , but the stretch elastic does work .