It means your engine is derated.
1- Your pulling hard and its getting the transmission overheated.- They you need to do a LTC (Low Temperature Circuit) bleed procedure that's in your operators manual. Your tractor does have two cooling systems, most people don't know this.
2- Depending on if you have a DE10 fuel pump. Most likely you do. you have a SCV problem. That's suction control valve. I have replaced many of these for your complaint. You will also want to do the fuel limiter if this is your problem. The dealer will have to hook up his computer to your tractor and do a graph reading of the actual vs desired rail pressure reading. This is a live test and nothing you can do about it without service advisor.
3- You may have a EGR sticking and overheating your air cooler. I have had many, many, many EGR's out b/c some idiot DTAC engineer thinks this causes derate issues. But with my experiences have only seen 1 actually be bad. Its a pain to remove and clean. Again, your dealer could hook up his laptop and do a cycle test to eliminate. Not much you can do though.
4- Your LTC circuit again could be needing bled and have an air pocket in the air cooler causing the code to set.
Remember that the LTC circuit and your normal cooling circuit isn't the same. Your radiator is split and the temp reading on the dash isn't what the temp reading your ECU is picking up. The dash or BIF(Basic informatory) reads temp off the head like any temp guage would on an engine. Your ecu reads temp from trans temp, air temp, and coolant temp. If any of these perameters aren't within spec. It will protect itself by derating the tractor.
Remember- You wont see the tractor getting hot. There are no codes or lights that come on when all this happens. Other than the tractor derating.