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Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 3304
Experience:  ASE Med/HD Truck Technician, NATEF Diesel Engines and Electrical/Electronics Technician, EPA 608/609 HVAC Certified, Steering/Suspension and ABS/Brakes Technician
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We have an isx cummins peterbuilt 2008. Check engine light

Customer Question

We have an isx cummins peterbuilt 2008. Check engine light is on and we can't get it to idle up and speedometer is saying 25 when we are parked and not going.
Submitted: 2 years ago.
Category: Medium and Heavy Trucks
Expert:  Jeremy replied 2 years ago.
My name is ***** ***** I will assist you with your concerns.
The truck will not idle because the speedometer has a signal issue. It knows that because the ABS sensors are reading that the truck isn't moving.
The code may be related to that.
Are you going to fix yourself? I would try first replacing the speed sensor and see if that resolves the speedometer issue since they are pretty cheap.
If no luck, then the truck will need to be scanned to see what the codes are. Without those codes, it could be a number of things triggering the truck to be in limp mode.

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