Deere 331g Pin# 1T0331GKPHF311886. Engine is in derate after a def system issue warning and countdown. Only active codes i have are DCU 523636, DCU 3516. I drained tank and the fluid looks fine. I changed the dosing filter and the old filter looked fine. I am leaning towards the header unit but not 100% sure. Any help would be appreciated. Thank you. Machine has 1390 hours.
You will most likely need a new DEF header. The DEF header has been updated. Your machine does need all the softwares updated. You may want to try that first since the DCU is one of the softwares that need updating. The new DCU software does address nuisance DEF Quality codes.
Thank you.