Usually this message on an ISX is about the EGR. What type of engine and year check flash codes than google code to find problem I suggest registering on cummins quick serve online it is free and it will take your engine serial number and than you have all manuals for free!!!! There are several ways now a days to get flash codes if you have an info center on the cluster there a control on right side of sterring wheel on the column. If not look for a switch labeled DIAG this will flash out codes via check engine light. Or put cruise switch on and use accl/decl switch to flash out code. Count the blinks this is your fault. The fault code will flash in the following sequence: First, a WARNING (yellow) light will flash.

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2016 peterbilt 389Peterbilt 2016 Operators Manual

2016 Peterbilt 389

389

Operators Manual 2016 Peterbilt 389

Then there will be a short 1- or 2-second pause after which the number of the recorded fault code will flash in (red) STOP. There will be a 1- or 2-second pause between each number. When the number has finished flash ing in red, a yellow light will appear again.

The three-digit code will repeat in the same sequence. The lights will continue to flash the same code until the system is told to do something else. To go to the next fault code, move the cruise control/PTO switch momentarily to the RESUME/ACCEL position. You can go back to the previous fault code by momentarily moving the cruise control/PTO switch to the SET/COAST position. If only one active fault is recorded, the system will continuously display the same fault code when either the RESUME/ACCEL or SET/COAST switch is depressed.