Patterns of DTC Indications: The DTC consists of a main code and sub-code. Reading the main code: In case of 1 ~ 10 Count the number of blinks. In case of 11 ~ 15 Four continuous blinks count as ten. Add any further blinks together as shown. Reading the sub code: Count the number of blinks. If the main code is '3' and the sub-code is '4', record a DTC 3-4.