4 Upon punching in the “unlock” code and the Mini Maxx reading the ECU files, you can change a number of options. If you’re racing your diesel truck, you can use the Mini Maxx to disable the EGR system, the DPF, or the UREA system. Tire calibration is available if you have lifted your truck and added larger tires. You can adjust the speed limiter or remove it completely. You can clear DTCs (diagnostic trouble codes). And we were able to disable the TPMS (tire pressure monitoring system) that just beeped at us all the time. The TPMS is adjustable via the Mini Maxx, but we were happy to just disable it.