ACDelco GM Genuine Parts Flex Fuel Sensors

GM Flex Fuel Sensor (13507128)

The OEM ethanol content sensor and the standard for any flex fuel conversion. Every major standalone ECU reads this sensor natively — Haltech, Link, MoTeC, and the Hondata and KTuner flex packages all expect its output — which is why it's the one that shows up on essentially every E85 build regardless of platform.

It reads the ethanol percentage and fuel temperature in real time and outputs a frequency signal the ECU uses to blend between gas and ethanol fuel maps. That's what makes a true flex build work: fill with whatever the pump has, and the tune follows.

GM Genuine Parts / ACDelco, manufactured to GM OE specification for fit, form, and function. Also cross-references to the VDO/Continental SE1004S and GM 13577429.

Specs: 3/8" EFI quick connect on both inlet and outlet. Three-pin electrical connection — power, ground, and signal output.

Plumbing: the sensor goes inline in the feed, typically between the pump and the fuel rail, or in the return depending on your setup. Mount it where it stays full of fuel.

Mating electrical connector and fittings are not included. You'll want the pigtail and AN adapters — 6AN or 8AN to 3/8" quick connect — to plumb it into an aftermarket fuel system. Worth ordering together; it's the most common follow-up call on this part.