DTC Codes by System
1,582 OBD-II powertrain diagnostic trouble codes grouped by subsystem. Each system page lists every code in that category with descriptions and ECU-tuning suppression context.
Generic Sensor / Circuit
2807 codes
Generic sensor circuit, range/performance, signal voltage, and open/short OBD-II codes.…Cooling System
1089 codes
Coolant temperature, thermostat, and cooling fan OBD-II codes.…CAN / Communication
1002 codes
CAN bus, module communication, and network OBD-II codes (U-codes territory).…Other Powertrain
962 codes
Miscellaneous powertrain OBD-II codes not classified into specific subsystems.…Fuel System
924 codes
Fuel injector, fuel pump, fuel pressure, and fuel rail OBD-II codes — with diagnostic notes for tuners.…Transmission
422 codes
Gearbox, TCM, clutch, and shift solenoid OBD-II codes.…Misfire / Cylinder
380 codes
Cylinder misfire, multiple misfire, and cylinder-specific OBD-II codes — and why never to suppress.…AdBlue / SCR / NOx
376 codes
AdBlue, SCR, urea dosing, and NOx sensor OBD-II diagnostic trouble codes — with technical and legal context for off-road suppression.…Turbo / Boost
316 codes
Turbocharger, wastegate, boost pressure, and supercharger OBD-II diagnostic trouble codes — with tuning context.…Camshaft / VVT / Timing
258 codes
Camshaft position sensor, VVT/VANOS, and timing OBD-II codes.…O2 / Lambda Sensor
178 codes
Oxygen sensor, lambda sensor, and AFR OBD-II diagnostic trouble codes — with tuning context.…Throttle / Pedal
174 codes
Electronic throttle body, accelerator pedal position sensor OBD-II codes.…Ignition / Knock
161 codes
Ignition system, knock sensor, spark control OBD-II codes — and why these should never be suppressed.…EGR
160 codes
All EGR-related OBD-II diagnostic trouble codes. EGR valve faults, flow performance, position sensor, cooler issues — with off-road suppress…DPF / Particulate Filter
91 codes
All OBD-II diagnostic trouble codes related to the diesel particulate filter (DPF), gasoline particulate filter (GPF), and soot management —…Catalyst
70 codes
Catalyst efficiency below threshold and three-way catalyst OBD-II codes — context for de-cat downpipes and motorsport use.…Air Metering (MAF / MAP)
45 codes
Mass airflow, manifold absolute pressure, and barometric sensor OBD-II codes.…