Cummins ISB CM550 (1990-94) Fault Code: 264 PID: 181 SPN: 174 FMI: 2 Fuel Temperature Sensor Error

Circuit Description
This fault indicates a final defect of the temperature sensor. The sensor’s reading indicates an unrealistic value, or the temperature is outside of the signal range check thresholds, -45°C [-49°F] to 130°C [266°F].

Component Location
The circuit for this fault code is contained within the Bosch® fuel pump control module.

Shop Talk
The table below relates which actions are taken by the engine control module (ECM) or fuel
pump control module when Fault Code 264 becomes active. When a defect occurs within the controller temperature sensing circuit, the controller defaults to a temperature value of 75°C [167°F]. If this is the temperature’s reading indicated on the monitor screen and this reading does not vary with changes in the coolant temperature, then the is most likely malfunctioning.

NOTE: An active pump fault code can result in deactivation of the fuel lift pump by the ECM.
Correct the active fault codes before replacing the fuel lift pump.