Komatsu WA270-8 wheel loader Serial #A28239 VIN # KMTWA13HHNA28239 We are having after treatment issues. 3714, 4863, 4572, 5176, 3868 these codes come up. We have checked all the fuses. The nozzle was plugged. We resolved the issue & primed the system. The light went out for a short time then came back on and derated. I appreciate any advice on how to test this.
Odds are your DEF sensor has failed. Check voltage to sensor, if you've got 24 v present and implausible values, you need a sensor. Not a bad job, just tedious.