Mechanical systems
Reference overviews of aftertreatment, transmission, braking, electrical sensing, and cooling—then jump to the related fault codes.
What severity means
Every code sheet uses one of these three levels. They are practical driving guidance — not a legal ruling.
- OK to driveYou can usually keep driving for short trips, but schedule a diagnosis soon.
- Check soonHave the vehicle checked soon; avoid long trips if symptoms worsen.
- Stop the vehicleStop driving when safe and have the vehicle inspected before continuing.
Aftertreatment & emissions systems
DPF, SCR, DEF, NOx probes, EGR, and EVAP on one exhaust story.
Open system page · 21 codes
Transmission control & ratio monitoring
TCM shifting, ratio checks, and limp-mode messenger logic.
Open system page · 7 codes
Electrical sensing & powertrain inputs
Sensors, heaters, supply voltage, CMP, rail pressure, and boost paths.
Open system page · 24 codes
Engine cooling & overheat protection
Coolant paths, level probes, thermostat regulation, and shutdown logic.
Open system page · 8 codes