J1939 Data Link - Abnormal Update Rate (Data Link)
The CAT-CID247-FMI9 (Caterpillar) diesel fault code means: J1939 Data Link - Abnormal Update Rate (Data Link). This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- 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
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.
Frequently Asked Questions
What does CAT code CID247-FMI9 mean?
CAT code CID247-FMI9 (J1939 Data Link - Abnormal Update Rate (Data Link)) is a serious-severity fault on Caterpillar on-highway diesel engines. CID 247 is the J1939 Data Link, measuring vehicle J1939 bus communications. 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 CID247-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 CID247-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.
Sources
This page is built from documented references. Verify against your own service info before repair work.