Truck gets to 100km then derates

JOSHNW

MEMBER
2007 ISUZU TRUCK
6 CYL
MANUAL
113,000 MILES

I have a FTS 750 2007 modle. When cold I drive up to 103 kph and service soon light comes on and engine derates back to 80kph.
If I then stop and turn the truck off and restart it I can only get to 40 kph and service soon light comes on and it will slowly clim to 80 kph
What could be causing this?

1 Reply

WRENCHTECH

MECHANIC
20,761 POSTS

The "check engine" light is an indicator for a system that monitors many electronic functions in the system, also called the "malfunction indicator lamp" (MIL). It can come on for any of hundreds of different causes from any of the systems that the computer monitors. Some are very important and can lead to further component or engine damage and some are emissions related not as serious but still a problem and need to be repaired.

Your first step is to have the computer scanned to retrieve the trouble codes that were set when the check engine light came on. Those codes will give you specific information about what the computer saw and will get you pointed in the right direction to find your problem. With a 1996 or newer and some 95 cars and you have an AutoZone or Advanced auto parts in your area, they will read them for free. Once you have these code numbers, we can be a lot more specific about what your problem may be.