Service Interaction Protocol
Clear Diagnostic Info
OPERATION
DTC_TARGET
STORAGE_TYPE
Permanent DTCs: This service typically does not clear “Permanent DTCs” (as defined by OBD-II). Those usually require a successful driving cycle to clear automatically by the ECU logic.
Overview
“The client uses this service to clear one or more units of diagnostic information from the server’s memory. This includes DTCs, captured data, and status counters.”
This service is the destructive counterpart to Read DTC Information (0x19). It resets the internal fault counters and aging statistics.
Default Behavior
Diagnostic Trouble Codes (DTCs) and snapshots are stored in Non-Volatile Memory (NVM). They persist through power resets and battery disconnects. Information is only cleared when a valid 0x14 request is received or if a “permanent” fault is cleared by the ECU after a successful repair and verification cycle.
Protocol Anatomy
◆ PROTOCOL ANATOMY
0x14 CLEAR DIAGNOSTIC INFO
0x14 RESPONSE
Group of DTC Parameter
The 3-byte GroupOfDTC parameter allows specific targeting of fault groups. The most common use case is clearing all code.
Clears all diagnostic info including DTCs, freeze frames, and extended data.
Request
14 FF FF FFTargets only OBD-II/Emissions related faults.
Request
14 00 00 00Example: Targeting only P-codes (implementation dependent).
Request
14 FF FF 00Example: Targeting only communication U-codes.
Request
14 C0 00 00Workflow & Response Pending
ECU logic for clearing diagnostic trouble codes and snapshots.
Internal logic flow for clearing diagnostic information from memory.
Clearing memory (writing to EEPROM or Flash) can be a slow operation. If it takes longer than the standard response time (approx 50ms), the ECU will send NRC 0x78 (Response Pending). This tells the tester to wait and prevents a timeout.
Long Operation Workflow (NRC 0x78)
5 stepsNegative Response Codes
Error_Catalog