Engine Coolant Temperature - Voltage Below Normal (Short to Low)
The CAT-CID110-FMI4 (Caterpillar) diesel fault code means: Engine Coolant Temperature - Voltage Below Normal (Short to Low). This is a moderate severity code.
Unverified. We could not confirm this code's definition against freely available manufacturer documentation, so treat the meaning, severity and fix guidance on this page as unconfirmed. Check it against the manufacturer's service information for your exact model and serial range before acting on it. This page is kept out of search engines for that reason, and we are working through this family manual by manual.
- Keep driving?
- Short distances only
- DIY difficulty
- intermediate
- Estimated cost
- $150-$500
Down with a CAT fault on the road?
We are building a network of verified mobile diesel and reefer technicians along the freight corridor. It is not live yet — no one can be dispatched to you today. You can see where the pilot is launching and register interest.
View pilot availability →What Are the Symptoms of CAT-CID110-FMI4?
- Check Engine Light
- Sensor reads opposite extreme on CAT ET
- Possible derate or false operating condition
What Causes CAT-CID110-FMI4? (Most Likely First)
- Signal wire shorted to ground Very Likely
- Sensor internally shorted Likely
- Moisture or contamination in connector Possible
Can I Still Drive with CAT-CID110-FMI4?
Short distances only. CAT-CID110-FMI4 is rated moderate severity. Keep trips short and get it diagnosed soon rather than waiting for symptoms to worsen.
Frequently Asked Questions
What does CAT code CID110-FMI4 mean?
CAT code CID110-FMI4 (Engine Coolant Temperature - Voltage Below Normal (Short to Low)) is a moderate-severity fault on Caterpillar on-highway diesel engines. CID 110 is the Engine Coolant Temperature, measuring coolant temperature. FMI 4 (Voltage Below Normal (Short to Low)) indicates the specific fault mode. Use CAT ET to confirm before replacing parts. Diagnose with CAT ET (Electronic Technician) software.
Can I drive my truck with CAT code CID110-FMI4?
Short distances may be acceptable, but running long with this fault risks progressive damage or forced derate. Address promptly.
How much does it cost to fix CAT CID110-FMI4?
Typical repair is $150-$500. Sensor / wiring fixes fall at the low end; injector, HEUI pump, turbo, or aftertreatment work falls at the high end. CAT dealer labor often requires CAT ET for calibration and parameter programming.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose CAT-CID110-FMI4?
Confirm active fault in CAT ET.
Disconnect sensor; if the reading flips to the opposite extreme, the sensor is internally shorted.
If reading stays pinned, measure signal wire to ground with sensor unplugged; a short confirms harness damage.
Repair harness chafe or replace sensor as determined.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J1939-73Application Layer: Diagnostics (defines the SPN/FMI fault-identifier framework)
Which Vehicles Commonly Get CAT-CID110-FMI4?
- Freightliner Classic XL with CAT C15
- Peterbilt 335 with CAT C7
- Peterbilt 386 with CAT C15
- Kenworth T800 with CAT C15
- Western Star 5900 with CAT C15
- Peterbilt 389 with CAT C15
- Peterbilt 387 with CAT C15
- Kenworth T470 with CAT C9
- Kenworth T800 with CAT C13
- Peterbilt 386 with CAT C13
- Thomas / Bluebird school bus with CAT C7
- Peterbilt 387 with CAT C13
- Peterbilt 340 with CAT C9
- Peterbilt 379 with CAT C15
- Kenworth T370 with CAT C7
- Kenworth T660 with CAT C13
- International 9400i with CAT C15
- Kenworth W900 with CAT C15
- Freightliner Columbia with CAT C13
- International 9200i with CAT C13
- International 4300 with CAT C7
- Western Star 4900 with CAT C15
- Freightliner M2 106 with CAT C7
- IC Bus shuttle with CAT C7
- International 9200i with CAT C15
- Kenworth T2000 with CAT C15
Explore More
Was this helpful?
Send this to whoever is fixing the truck — your tech, or the person asking what the fault means.