"OBD0" is not an official standard like OBD2. It is most usually used to refer to MPFI ECUs made from 88-91 with Electronic Advance Distributors found on OBD0 MPFI cars of this era. Technically, all ECUs made prior to 1988 and all accord/prelude/v6/OBD0 Vtec ECUs of this era are also "OBD0" but due to the drastic differences, they are grouped seperately and referred to as "pre-OBD" ECUs, or another term.

OBD0 ECUs (88-91)

• PG7 : 88-89 Integra (D16A1)
• PM6 : 88-91 Civic/CRX SOHC Si (1.6l sohc)
• PM7 : 89-91 Civic Si DOHC ZC (JDM EF3)
• PM7 : 89-91 CRX D16A8 , D16A9 ( EDM )
• PM8 : 88-91 CRX HF
• PR3 : 89-91 JDM B16A EF8/9
• PR5 : 90-91 JDM Integra ZXi (1.6 sohc)
• PW0 : 89-91 JDM/Euro B16A EF8/9 DA6-XSi (DOHC VTEC)
• PR4 : 90-91 Integra LS/GS (b18a)
• PS9 : 88-91 4 door civic EX Auto (sohc 1.6)

The PH3 and PK3 ECU shares almost the same PC board.

• PK2 : 88-91 Prelude Si B20A engine DOHC 140 HP
• PH3 : 86-89 Accord 2.0Si B20A

These DPFI ECUs were also made during the same time period:

• PM5 : 88-91 Civic/CRX DX (DPFI D15b)
• PM9 : 88-91 Civic base model (DPFID15b)