Question : Working on a 98 kw w/cat 3126 & my code reader shows PID 128 004 11 with no explanation of code, truck has intermitant low power, thanks John.

Answer : Hey. A 128-4-11 diagnostic code for a 1998 3126B engine is indicating that you have an open or short in the #4 injector circuit. The most likely cause is a failed injector. However, I would check the wiring harness as well. You may find that the connector for the #4 injector is bad and needs to be replaced. Cat makes a repair kit for the injector connector if is bad.
Please let me know if you have any more questions.

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$28 : Working on a 98 kw w/cat 3126 & my code reader shows PID 128