SPN 97 FMI 3 Code on DD15 - Water in Fuel Voltage High

Question

I am getting a constant active SPN 97 FMI 3 code on my 2018 Freightliner Cascadia. The dash warning keeps flickering and I have replaced the fuel filter thinking that was it, but it came right back. The truck isn't derating yet but I don't want to get stuck on the road with a fuel issue.

Jake Morrison · Accepted Answer

The issue was a failed Water in Fuel sensor (Part # A0004702300) located at the bottom of the fuel processor. The internal resistor had failed causing the high voltage signal. I replaced the sensor, applied a small amount of dielectric grease to the connector, and cleared the codes with DiagnosticLink. The repair took about 20 minutes and the part was approximately $85 from the dealer.

Carlos Diaz · Answer

I have seen the pins inside the sensor connector get green crusty corrosion which causes high resistance. Try cleaning it with some CRC electronic cleaner and see if the code goes inactive.

Sam Holloway · Answer

Check your wiring harness pigtail right at the bottom of the fuel module. These vibrated a lot on the 2018 models and often rub through the insulation against the frame rail or the module housing itself.

Sarah Thompson · Answer

If you have DiagnosticLink, look at the actual voltage reading for the WIF sensor. An FMI 3 usually means an open circuit or a short to power, not necessarily actual water in the bowl.

SPN 97 FMI 3 Code on DD15 - Water in Fuel Voltage High

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