what are DTC codes and how to clear DTCs?

On this section you will read:

1. what are DTC codes (Diagnostic Trouble Codes)?
2. How a DTC code display?
3. Explanation of DTC Codes
4. How to clear DTCs?

DTCs or Diagnostic Trouble Codes are fault codes that are stored by the on-board computer diagnostic system and used by automobile manufacturers to diagnose problems related to the vehicle.

DTC code display

During the running of the vehicle, the electronic control unit system (ECU) monitors the automobile conditions of each component. If there is a trouble, the corresponding problem will generate fault code (named DTC code) and it's stored in code form, and then the fault running module function is started to ensure the car with trouble code can be driven to the repair shop for maintenance. Maintenance can use the diagnostic tools to call up the fault code and quickly locate the trouble, repair the fault and clear DTC codes.

On vehicles equipped with the OBDII system, all fault codes DTC begin with an English letter, followed by 4 digits. Such as P0101, C1234, B2236 and so on.

The letters at the beginning of DTC indicate diagnostic trouble, an analysis of a typical DTC code is shown below:

Explanation of DTC Codes

The first letter indicates the fault system

P - Power system

B - Body system

C - Chassis system

U - Network or data communication transmission system

The first number means the fault code type

0 - Generic OBD code

1 - Vehicle manufacturer-specific code

The second number indicates the type of fault system

1 - Fuel and air metering systems

2 - Fuel and air metering systems (injection circuit)

3 - Ignition systems or misfire

4 - Auxiliary emission system

5 - Vehicle speed control & idle speed control system

6 - Computer output circuit

7,8,9 - Gearbox

The last two digits indicate the fault description. 

Usually, you can use diagnostic & scanner tools to read and clear DTC codes by yourself. The following is a video about how to use an Autel AutoLink AL519 to read and clear DTC codes.

how to use an Autel AutoLink AL519 to read and clear DTC codes

Source: https://www.obdprice.co.uk/blogs/news/what-are-dtc-codes-and-how-to-clear-dtcs

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