Originally Posted by Modshack

You may want to be careful going past the click. Some cars will backflow fuel into the Charcoal emissions canister resulting in a CEL. This used to happen to my Daughter with her Mazda 3 until I retrained her. Not a problem since.

On the Fuel sender contacts, they look much like this. Since the "Full" contact us largely exposed to air, it can corrode and interupt the signal. Techron is effective at keeping these contacts scrubbed clean and all lights on the dash lit when full..