All UDS services

Tester Present

0x3E

The Tester Present service signals to the server that the diagnostic client is still connected, preventing the current session from timing out.

✕Negative response codes
0x130x220x310x330x72

Request

SID 0x3E · 2 bytes
Len (bits)
Parameter description
Value (hex)
8
Tester Present SID
0x3E
1
suppressPosRspMsgIndicationBitBit 7 of the sub-function byte. When set to 1, the server will not send a positive response.
7
zeroSubFunctionSub-function value fixed to zero (no additional behavior).

Positive response

SID 0x7E
Len (bits)
Parameter description
Value (hex)
8
Tester Present SID
0x7E
1
Echo of suppressPosRspMsgIndicationBit
7
Echo of zeroSubFunction
PREVIOUSWrite Memory By Address0x3DNEXT Secured Data Transmission0x84