There are ten OBD-II PIDs modes of operation described in the latest OBD-II standard SAE J1979. They are as follows (the $ prefix indicates a hexadecimal radix):
$01. Show current data
$02. Show freeze frame data
$03. Show stored Diagnostic Trouble Codes
$04. Clear Diagnostic Trouble Codes and stored values
$05. Test results, oxygen sensor monitoring (non CAN only)
$06. Test results, other component/system monitoring (Test results, oxygen sensor monitoring for CAN only)
$07. Show pending Diagnostic Trouble Codes (detected during current or last driving cycle)
$08. Control operation of on-board component/system
$09. Request vehicle information
$0A. Permanent DTC’s (Cleared DTC’s)
Vehicle manufacturers are not required to support all modes.
Each manufacturer may define additional modes above #9 (e.g.: mode 22 as defined by SAE J2190 for Ford/GM, mode 21 for Toyota) for other information (e.g.: the voltage of the Traction Batter
