Diagnostic Trouble Codes

DiagnosticTrouble.com was developed by experts in automotive service industry to help diagnose cars and assist in troubleshooting procedures.

What is diagnostic trouble code ?

Diagnostics Trouble Codes (DTCs) are codes that the vehicle's electronic control unit generates when it detects malfunction or other issues.

The codes in all these different types are grouped into four categories:

Pxxxx codes relate to powertrain
Bxxxx codes relate to body
Cxxxx codes relate to chassis
Uxxxx codes relate to network or undefined

The OBD 2 Diagnostics trouble process is preformed by your cars onboard computer system using sensors located throughout your car's engine, drive train(p), chassis(c), body(b), and network communication(u) systems. Some fault codes indicate real problems with your vehicle and some indicate faulty sensors

Diagnostic Trouble Codes (DTCs) are meant to guide you to the proper service procedure in the vehicle's service manual. DO NOT replace parts based only on DTCs without first consulting the vehicle's service manual for proper testing procedures for that particular system, circuit or component. DTCs are alphanumeric codes that are used to identify a problem that is present in any of the systems that are monitored by the on-board computer (PCM). Each trouble code has an assigned message that identifies the circuit, component or system area where the problem was found.

DTCs are alphanumeric codes that are used to identify a problem that is present in any of the systems that are monitored by the on-board computer (PCM). Each trouble code has an assigned message that identifies the circuit, component or system area where the problem was found. OBD2 diagnostic trouble codes are made up of five characters:

DTC vs MIL

When the vehicle's on-board computer detects a failure in an emissions-related component or system, the computer's internal diagnostic program assigns a diagnostic trouble code (DTC) that points to the system (and subsystem) where the fault was found. The diagnostic program saves the code in the computer's memory. It records a 'Freeze Frame' of conditions present when the fault was found, and lights the Malfunction Indicator Lamp (MIL). Some faults require detection for two trips in a row before the MIL is turned on.

How to find diagnostic trouble code ?

Data link connector location is under dashboard on driver side of car.

If data link connector is not located under dashboard, a labe should be there telling where the connector can be found.

Latest Added DTC's

Powertrain Codes	Network Codes	Chassis Codes	Body Codes
P0249 Code P003D Code	U1335 Code U0268 Code	C144B Code C2931 Code	B0286 Code B0153 Code

Don't Forget (Before & After DTC Check)

Sometimes when a Check Engine Light comes on the vehicle's engine computer will go into a "back-up" or "limp-home" mode. This allows the vehicle to continue operating until repairs can be made. Back-up or limp-home modes are not the most emission or fuel efficient way for the vehicle to operate. The problem needs to be repaired.

The Check Engine Light will stay on until the readiness monitor related to that fault has been reset and the sensor that was recorded out-of-range is seen as within range again.