What is a DTC fault code?

A Diagnostic Trouble Code is a standardized notation generated by the vehicle's Electronic Control Unit (ECU) when it detects a fault or abnormality. Each code is linked to a specific component or system.

Structure of fault codes

A typical DTC code (e.g., P0301) consists of four parts:

  • P = Powertrain, B = Body, C = Chassis, U = Network
  • 0 = Generic (SAE standard), 1 = Manufacturer-specific
  • 3 = System category (e.g., ignition)
  • 01 = Specific fault (e.g., cylinder 1 misfire)

How does FTLink help?

The FTLink system reads and records DTC codes in real-time. It displays the fault code with an explanation and sends an alert to the fleet manager, so the issue can be addressed before it becomes serious.