Engine Speed / Crankshaft Sensor - Abnormal Frequency, Pulse Width, or Period
The CAT-CID190-FMI8 (Caterpillar) diesel fault code means: Engine Speed / Crankshaft Sensor - Abnormal Frequency, Pulse Width, or Period. This is a serious severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- intermediate
- Estimated cost
- $250-$1200
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-CID190-FMI8?
- Check Engine Light
- Frequency or pulse width out of range
- Speed, crank, or cam signals dropping out
What Causes CAT-CID190-FMI8? (Most Likely First)
- Damaged tone ring or target wheel Likely
- Sensor air gap incorrect or debris on tip Likely
- Wiring shield damaged causing signal noise Possible
Can I Still Drive with CAT-CID190-FMI8?
Short distances only. CAT-CID190-FMI8 is rated serious severity. Keep trips short and get it diagnosed soon rather than waiting for symptoms to worsen.
Frequently Asked Questions
What does CAT code CID190-FMI8 mean?
CAT code CID190-FMI8 (Engine Speed / Crankshaft Sensor - Abnormal Frequency, Pulse Width, or Period) is a serious-severity fault on Caterpillar on-highway diesel engines. CID 190 is the Engine Speed / Crankshaft Sensor, measuring primary crank speed signal. FMI 8 (Abnormal Frequency, Pulse Width, or Period) 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 CID190-FMI8?
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 CID190-FMI8?
Typical repair is $250-$1200. 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-CID190-FMI8?
Verify air gap at the sensor tip per CAT service manual.
Inspect the tone or target wheel for damage, debris, or missing teeth.
Scope the signal during cranking and running for missing pulses or noise.
Replace sensor, clean target, or repair wiring as indicated.
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-CID190-FMI8?
- 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.