SPN 105 FMI 0 — Intake Manifold (Charge Air) Temp — High
Intake-manifold (charge-air) temperature is above the high limit. Hot intake air hurts power and combustion and the ECM will derate. It usually points to a charge-air-cooler (CAC) airflow or EGR-related problem.
Your SPN/FMI rides along, so nearby mechanics see the fault before they quote you.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Plugged/bug-packed CAC or radiator face restricting airflow
- CAC leak or restriction reducing cooling
- EGR over-flowing hot gas into the intake
- Intake-air temp sensor fault reading high (verify first)
First moves (roadside)
- Inspect the CAC and radiator face for bugs, mud, and debris blocking airflow.
- Check for CAC leaks/restriction and loose charge-air piping/boots.
- Reduce load on grades to keep intake temps in range until repaired.
- Confirm the reading is real before replacing the sensor.
Common misdiagnoses
- Replacing the sensor when a packed CAC face was the airflow restriction.
- Missing a charge-air leak that drives temps up.
- Ignoring an EGR fault adding heat to the intake.
FAQ
Intake-manifold (charge-air) temperature is above the high limit. Hot intake air hurts power and combustion and the ECM will derate. It usually points to a charge-air-cooler (CAC) airflow or EGR-related problem.
Serious — Power derate likely — plan to stop soon.
The most common cause is: Plugged/bug-packed CAC or radiator face restricting airflow. Other possibilities include CAC leak or restriction reducing cooling; EGR over-flowing hot gas into the intake; Intake-air temp sensor fault reading high (verify first).
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Find a mechanic or related guides
General diagnostic guidance for heavy-duty diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack). Not a substitute for a scan-tool diagnosis on your specific truck.