MB SD C4/C4+: How to Repair DoIP

If anyone has problems with MB SD Connect C4/C4+ DoIP connection, check the voltage on the 8th leg of the OBD connector when the Doip connection is turned on, a voltage of 6.5V should appear

How to Check Mercedes MB STAR C4 devices using the DOIP protocol using a multimeter.:

Test Mb Sd C4 Doip 1

Test Mb Sd C4 Doip 2

Test Mb Sd C4 Doip 3

Test Mb Sd C4 Doip 4

VXDIAG Benz multiplexer works the same way.


For those who do not have voltage, we disassemble the C4 or C4 + device, we find the diode as in the photo (circled in red) and look at the value, if it is different, then change it to the one in photo 3, we also measure the voltage on the diode itself. All this applies only to devices where there is DOIP in the configuration.

Mb Sd C4 Board 1

old style C4 board

Mb Sd C4 Plus Board 1

New SD C4+ board

Mb Sd C4 Plus Board 2

Diode replacement.

solder the diode and everything after this before and after works great

Test Mb Sd C4 Doip 6 Test Mb Sd C4 Doip 7

The exchange of diagnostic information over Internet Protocol (DoIP) is performed using a standardized service interface as specified in the ISO14229-2 standard.