Need help diagnosing a high exhaust gas temp derate on a caterpillar C7. What would cause high exhaust gas temp that would go high enough to derate the power. All this happens with an unloaded truck so it is not being overworked.
Hi. Thanks for using JA! I will try and help you out.Could you get me the engine serial number?
Thanks for the information.There are three sensors that control this derate. Atmospheric pressuree sensor, intake air temp, and timing sensors.Basically, when the engine is at high altitude and the intake temp heats up and the engine is under load, this derate will happen. It is more common out West. If your engine is under these conditions, there is not anything you can do about this.However, it is possible that your atmospheric pressure sensor is reading wrong causing this to happen. You could also have the intake air reading wrong as well.Where are you located? Are you out west?Do you know if this problem is new? Or has it always been happening?
We are in south Louisiana.
Atmospheric pressure sensor makes sense. I had a code that was logged about 9 hrs ago that is now inactive, "atmospheric pressure sensor input voltage high". It is inactive but still getting a derate. Should i just change it and see what happens?
I see. If you are located there, this code should pretty much not ever happen. We mainly see it at high altitudes.I would suspect you have an atmospheric sensor problem.
Just in case that doesnt do it, how can i tell if it is the timing sensors? Any test we can do or something on Cat ET that can tell us?
To be honest, the only reason the book says timing sensors is because of rpm's. I'm sure your timing sensors are fine. This code will only happen at higher rpm's under load.
I am ASE Master Truck Certified.