OBD-II Diagnostic Trouble Code (DTC)
OBD-II Diagnostic Trouble Code (DTC)
How to Read DTC and 1st Trip DTC
DTC and 1st trip DTC can be read by the following methods.
( with SDT or GST) SDT or GST (Generic Scan Tool) Examples: P0705, P0720 etc.
These DTC are prescribed by SAE J2012.
(SDT also displays the malfunctioning component or system.)
- 1st trip DTC No. is the same as DTC No.
- Output of the diagnostic trouble code indicates that the indicated circuit has a malfunction. However, in case of the Mode II and GST, they do not indicate whether the malfunction is still occurring or occurred in the past and returned to normal.
SDT can identify them as shown below, therefore, SDT (if available) is recommended.
Freeze Frame Data and 1st Trip Freeze Frame Data
The ECM has a memory function, which stores the driving condition such as fuel system status, calculated load value, engine coolant temperature, short term fuel trim, long term fuel trim, engine speed and vehicle speed at the moment the ECM detects a malfunction.
Data which are stored in the ECM memory, along with the 1st trip DTC, are called 1st trip freeze frame data, and the data, stored together with the DTC data, are called freeze frame data and displayed on SDT or GST. The 1st trip freeze frame data can only be displayed on the SDT screen, not on the GST. For detail, refer to [On Board Diagnosis Function] OBD System Introduction.
Only one set of freeze frame data (either 1st trip freeze frame data of freeze frame data) can be stored in the ECM. 1st trip freeze frame data is stored in the ECM memory along with the 1st trip DTC. There is no priority for 1st trip freeze frame data and it is updated each time a different 1st trip DTC is detected. However, once freeze frame data (2nd trip detection/MIL on) is stored in the ECM memory, 1st trip freeze frame data is no longer stored. Remember, only one set of freeze frame data can be stored in the ECM. The ECM has the following priorities to update the data.
Both 1st trip freeze frame data and freeze frame data (along with the DTC) are cleared when the ECM memory is erased.
How to Erase DTC
The diagnostic trouble code can be erased by SDT, GST or ECM DIAGNOSTIC TEST MODE as described following.
- If the battery cable is disconnected, the diagnostic trouble code will be lost within 24 hours.
- When you erase the DTC, using SDT or GST is easier and quicker than switching the mode selector on the ECM.
The following emission-related diagnostic information is cleared from the ECM memory when erasing DTC related to OBD-II. For details, refer to On Board Diagnosis Function (QR25DE) or [On Board Diagnosis Function] On Board Diagnosis Function (VQ40DE).
- Diagnostic trouble codes (DTC)
- 1st trip diagnostic trouble codes (1st trip DTC)
- Freeze frame data
- 1st trip freeze frame data
- System readiness test (SRT) codes
- Test values
How to Erase DTC (With SDT)
1) The emission related diagnostic information in the TCM and ECM can be erased by selecting "ALL Erase" in the "Description" of "Retrieving all DTCs" mode with SDT.
How to Erase DTC (With GST)
1) If the ignition switch stays "ON" after repair work, be sure to turn ignition switch "OFF" once. Wait at least 10 seconds and then turn it "ON" (engine stopped) again.
2) Select Mode 4 with the Generic Scan Tool (GST). For details refer to [OBD System: GST (Generic Scan Tool)] OBD System GST (Generic Scan Tool) (QR25DE) or [OBD System: GST (Generic Scan Tool)] OBD System GST (Generic Scan Tool) (VQ40DE).
How to Erase DTC (No Tools)
1) Disconnect battery for 24 hours.
2) Reconnect battery.