Cummins ISB CM550 (1990-94) Fault Code: 155 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, cold start aids, 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.

Shop Talk
1) Make sure the engine compartment temperature does not get too high (above 93.3°C
[200°F]).
2) Make sure the intake manifold temperature sensor is not located near any extreme heat
sources.

Possible causes:
1) Clogged, dirty, inadequate capacity air cleaner element. 010-060 through 010-063 in the
Troubleshooting and Repair Manual, ISB Engines, Bulletin No. 3666193.
2) Intake restriction. 010-059 in the Troubleshooting and Repair Manual, ISB Engines,
Bulletin No. 3666193.