Diagnostic Trouble Code (DTC)

What is a Diagnostic Trouble Code

The engine control system in your car can – up to a certain point – diagnose problems that may be affecting your vehicle’s emissions or engine performance. When some trouble is detected, the system returns a certain code, indicating the nature of the issue. The code returned is called a Diagnostic Trouble Code or DTC.

DTC Description

How is a DTC formed?

A DTC contains 5 digits, as shown below.

XXXXX

Each digit has a specific meaning.

P – Powertrain (Engine & Transmission)
B – Body (Includes A/C & Airbags)
C – Chassis (Includes ABS)
U – Network / Bus

0 – Generic
1 – Vehicle Specific

1 – Fuel & Air metering
2 – Fuel & Air metering (Injector circuit)
3 – Ignition System or Misfire
4 – Auxiliary Emission Controls
5 – Vehicle Speed Control & Idle Control System
6 – Computer Output Circuit
7, 8, 9 – Transmission
A, B, C – Hybrid propulsion

Fault Description

Example

DTC: U0609 – That’s a Network/Bus issue, generic in nature (not specific to this vehicle). It concerns the computer output circuit. Its classification is “09”, which matches a specific error description that will most likely help you find out what’s wrong with your vehicle.