SPN 174 — Engine Fuel Temperature 1
System: Fuel
Temperature of the fuel in the injection system. The engine computer uses it to correct fueling and may derate to protect the pump and injectors when fuel runs hot.
Can I keep running it?
MEDIUM — fix soon
Hot fuel lowers power and can damage the pump and injectors. Usually drivable carefully, but find out why it's hot.
Likely causes
- Running with a low tank in hot weather (little fuel to absorb return heat)
- Restricted or missing fuel cooler airflow
- High return flow from a leaking injector, relief valve or pump
- Fuel temperature sensor or wiring fault
Checks & fixes (easiest first)
- Fill the tank and recheck the reading
- Inspect the fuel cooler (if fitted) for debris and damage
- Measure injector and pump return flow per OEM
- Compare the sensor with an infrared reading and check its circuit
Common FMIs with SPN 174
- SPN 174 FMI 0Value too high (most severe)
- SPN 174 FMI 2Data erratic, intermittent, or incorrect
- SPN 174 FMI 3Voltage above normal or shorted high
- SPN 174 FMI 4Voltage below normal or shorted low
- SPN 174 FMI 15Value too high (least severe)
- SPN 174 FMI 16Value too high (moderately severe)
Related codes
Troubleshooting guides
FAQ
What does SPN 174 mean?
SPN 174 is Engine Fuel Temperature 1. Temperature of the fuel in the injection system. The engine computer uses it to correct fueling and may derate to protect the pump and injectors when fuel runs hot.
Can I keep running with SPN 174?
Hot fuel lowers power and can damage the pump and injectors. Usually drivable carefully, but find out why it's hot.
What causes SPN 174?
Running with a low tank in hot weather (little fuel to absorb return heat); Restricted or missing fuel cooler airflow; High return flow from a leaking injector, relief valve or pump; Fuel temperature sensor or wiring fault.