Use a stabilized 12V–13.8V power supply. Never use a battery charger.
A regulated (or a clean 12V automotive battery). An OBD2 Female Breakout Cable or individual jump wires.
Many online pinouts mislabel the Knock Sensor lines (pins 24 & 25 on the black connector) or swap Injector Grounds with Shield Grounds . The following data has been bench-tested. bosch me20 pinout verified
Connect your interface K-Line wire to Plug 4, Pin 11.
Do not use pin 1 or 32 on the grey connector – they are not connected (N/C) on ME20.4. Use a stabilized 12V–13
If the reading is 0V or significantly below 5V, an external engine sensor may be shorted internally, pulling down the entire 5V reference circuit. Disconnect sensors one by one to see if the voltage returns to 5V.
If you are attempting a boot-mode read to recover a bricked unit, a specific boot pin on the internal PCB circuit board must be grounded through a 10k-ohm resistor before powering up the board. An OBD2 Female Breakout Cable or individual jump wires
To perform a full read or write (EEPROM/Flash) in boot mode, a specific boot pin must be grounded or connected via a resistor: