Cylinder 4 Injector - Bad Intelligent Device or Component
The CAT-INJ4-FMI12 (Caterpillar) diesel fault code means: Cylinder 4 Injector - Bad Intelligent Device or Component. This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- advanced
- Estimated cost
- $400-$1800
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Common Symptoms
- Check Engine Light
- Dead cylinder
- Power loss
- CAT ET flags injector trim / solenoid coil failure
Probable Causes (Ranked by Likelihood)
- Internal injector electronic failure Very Likely
- Missing injector trim code in ECM Possible
Step-by-Step Diagnostic Procedure
Verify with CAT ET that the injector trim code matches the physically installed injector.
If trim is correct, perform cylinder cutout and solenoid resistance check.
Replace injector and program trim code.
Frequently Asked Questions
What does CAT code INJ4-FMI12 mean?
CAT code INJ4-FMI12 (Cylinder 4 Injector - Bad Intelligent Device or Component) is a serious-severity fault on Caterpillar on-highway diesel engines. This code flags cylinder 4 injector fault. CAT on-highway engines use HEUI (hydraulically actuated) injection pre-2007 and common rail post-2007. Confirm with CAT ET cylinder cutout test before replacing a $500-$800 injector. Diagnose with CAT ET (Electronic Technician) software.
Can I drive my truck with CAT code INJ4-FMI12?
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 INJ4-FMI12?
Typical repair is $400-$1800. 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.