Note in the instructions
https://www.jegs.com/InstallationIns.../121-84661.pdf that there is the chance, if you try really really hard, that you can put the magnet in backwards and the engine won't run.
Pay
particular attention to the stripe on the end of the magnet. If the car won't start after you put your magnetic pickup back in then you did indeed manage to put the magnet in backwards.