Engine lights make me crazy

One day when I was driving my 2012 kenworth t800 on I-70 the yellow engine light came on then after a while the red light came on with bipping. I stopped on shoulder . As soon as the wheels stopped the red light went away and yellow one stays on . I took it to kenworth and they fixed and changed several parts and sensors, including DEF system .I spent more than $8k . I picked up my truck and drove it about 300 miles the yellow light started on 1 minute and goes off every 10 to 15 minutes. Then red light came on as the first time . I took it again to kenworth . Then plugged the computer and they showed me all codes which is no one is activate . They said it maybe the fuel filter. I just ignored this issue and drive , when the red one comes on I stop and keep going again.