Cummins ISB CM550 (1990-94) Fault Code: 488 PID: 105 SPN: 105 FMI: 0 Intake Manifold Air Temperature Sensor – Engine Protection Circuit

Circuit Description
The intake manifold air temperature sensor is used by the electronic control module (ECM) to
monitor the temperature of the engine intake air. The intake air temperature is used by the
ECM for the engine protection system, and the timing and fueling control.
Component Location
The intake manifold temperature sensor is located on the side of the intake manifold, toward
the rear of the cylinder head, near cylinder No. 6.

Shop Talk
This is a warning fault code. If the intake manifold air temperature continues to rise, Fault Code
155 will become active and shut down the engine.

Possible causes:
1) clogged, dirty, inadequate capacity air cleaner element
2) faulty fan clutch
3) intake restriction
4) 010-031 in the Troubleshooting and Repair Manual, ISB Engines, Bulletin No. 3666193.