CORE ASSEM. 2Y5228 - Caterpillar

C-10 (8YS1-Up),
C-12 (9NS1-Up) Truck EnginesThe C-10 (8YS1-Up) and C-12 (9NS1-Up) Truck Engines use injector electronic trim codes to electronically trim the unit fuel injectors. The former C-10 (2PN) and C-12 (1YN) Truck Engines did not use or need injector electronic trim codes.
The engine personality module software compensates for variations in unit injector timing and fuel discharge, so that every electronically trimmed unit fuel injector functions as a NOMINAL injector. When manufactured, a four digit number (the electronic trim code) is marked on side of the injector valve assembly, just above the CAT® logo. See the illustration. This four digit number designates the injector's characteristics. The electronic trim code for each of the engine's unit injectors is programmed into the engine's personality module software at the time the engine is built.
(UNIT FUEL INJECTOR VALVE ASSEMBLY)
Electronic Trim Code (A). Serial Number (B). Serial Number Bar Code (C). Unit Fuel Injector Group Part Number (D). When a fuel injector group is serviced (changed), the new fuel injector group's electronic trim code must be programmed into the engine's personality module software by using the ET Service Tool calibration menu. If the new fuel injector group's electronic trim code is not entered, the previous fuel injector group's characteristics are assumed.
If it is not possible to immediately reprogram an injector's electronic trim code into the personality module software, the engine will not be severely harmed. The new electronic trim code should be reprogrammed as quickly as possible to optimize engine performance.