CAT Data Link (CDL) - Abnormal Update Rate (Data Link)
The CAT-CID248-FMI9 (Caterpillar) diesel fault code means: CAT Data Link (CDL) - Abnormal Update Rate (Data Link). This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- intermediate
- Estimated cost
- $300-$1500
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Common Symptoms
- Scan tool communication dropouts
- Dash cluster freezes or flickers
- Lost communication with other modules
Probable Causes (Ranked by Likelihood)
- Broken J1939 twisted pair or terminating resistor missing Very Likely
- Shorted bus wire on CAN_H or CAN_L Likely
- Failed module pulling the bus down Possible
Frequently Asked Questions
What does CAT code CID248-FMI9 mean?
CAT code CID248-FMI9 (CAT Data Link (CDL) - Abnormal Update Rate (Data Link)) is a moderate-severity fault on Caterpillar on-highway diesel engines. CID 248 is the CAT Data Link (CDL), measuring proprietary CAT service tool data link. FMI 9 (Abnormal Update Rate (Data Link)) 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 CID248-FMI9?
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 CID248-FMI9?
Typical repair is $300-$1500. 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
Step-by-Step Diagnostic Procedure
Measure J1939 bus resistance at the diagnostic connector with key off; expect about 60 ohms.
If resistance is wrong, locate both terminators and verify integrity.
Disconnect modules one at a time while monitoring CAT ET to find a module pulling the bus down.
Inspect the twisted pair for chafing, pinches, and moisture at splice packs.
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)
Commonly Affected Vehicles
- 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
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