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OBD or OBD-0 pertains to the 88-91 Honda/Acura era wiring, ignition, and ECU system. Unfortunately, OBD-0 has been phased out over the last 15 years or so due to OBD-1 being the superior ECU system to upgrade to for good reason, most notably for ECU chipping. However, here’s some technical tidbits – USDM lower grade EF civic/CRX models received a fuel economy 1.5L engine with Dual Point Fuel Injection (DPFi) that only used 2 fuel injectors. The higher grade Si & EX model civics received a more performance based 1.6L SOHC engine with Multi-Point Fuel Injection (MPFi) system running 4 injectors. All 90-91 Integra’s were 1.8L DOHC MPFi equipped. Over in Japan, there was a slew of low and mid grade civic models with 1.3/1.4/1.5/1.6 liter engines that were either carbureted or fuel injected. The upper grade models received 1.6L SOHC and DOHC engines (aka ZC) and finally the B16A in the top of the line Civic/CRX SiR as with the Integra RSi/XSi. The 89-91 JDM DA Integra wasn’t a very loved vehicle in Japan, but Honda offered some interesting model grades for the DA. Just like the EF civics, there were lower grade DA Integra models with a 1.6L SOHC ‘ZC’ carbed and fuel injection engine while a B16A was offered in the top grade RSi/XSi models.

OBD-0 visual indicators: Onboard ECU connector ports are green and black (see image below), dual distributor  connectors are an off-white color, a single wire narrowband 02 sensor,

OBD-0 Honda Vehicles

  • 88-91 EF Civic/CRX (US & JDM)
  • 88-89 Integra (US & JDM)
  • 90-91 DA Integra (US & JDM)



The 92-95 OBD-1 system is by far the most famous and favorable of them all. OBD-1 ECU’s are very chip friendly, though some of the JDM variant square type OBD-1 ECU’s are sensitive to what program is being used. It’s common now for 88-91 Civic/CRX/Integra enthusiasts to upgrade from OBD-0 to OBD-1 system.

OBD1 visual indicators: wire harness side have a grey colored slim 2-row pinned ECU connectors, M/T vehicles use all three A/B/C onboard ports (see image below), A/T vehicles use four onboard ports A/B/C/D, the distributor uses 2-grey plugs, a single 4-wire narrowband 02 sensor, gas saver model vehicles use a 5-wire 02 sensor, MAP sensor is now topside throttle body mounted (instead of firewall mounted), grey colored sensor and harness plugs are used throughout the engine bay.

OBD-1 Honda Vehicles

  • 92-95 Civic (US & JDM)
  • 92-95 Delsol (US & JDM)
  • 92-93 Integra (US & JDM)
  • 94-95 Integra (US & JDM)
  • 92-95 Prelude (US & JDM)
  • 92-95 Accord (US & JDM)



With the introduction of the restrictive “OBD2” system beginning in 1996, it shook Honda enthusiasts and ECU tuners alike because of the un-chip friendly OBD2 ECU. It introduced an all new ECU with smaller surface mount components and a very complicated and expensive processor chip. In Japan, aftermarket companies offered reprogramming services for JDM OBD2 ECU’s, unlike here in the states. From what I remember, there was only one place that offered OBD2 programming in Socal (no longer around).  Reprogramming and the chip were just too expensive for it to catch on. The aftermarket Honda world clapped back though, with the  invention of the ECU jumper harness allowing backwards OBD1 compatibility in OBD2 vehicles. The OBD2-A naming scheme was coined within the aftermarket community to help easily identify which OBD2 version is being dealt with whenever an OBD1 conversion is being performed and just in regular Honda banter between enthusiasts.

Honda also implemented a theft deterrent ‘Immobilizer’ system into some of the OBD2-A equipped vehicles such as the Prelude, Accord, and several other passenger vehicles. U.S. Civic’s and Integra’s did not receive any immobilizer system but U.K. based Civic and Integra’s did.

OBD2A visual indicators include: M/T vehicles use onboard ECU ports A/C/D (B is blank) – see image below, A/T vehicles use all four onboard ECU connectors, wire harness side ECU connectors are a new grey tall + wide connector style (C connector is blue), the distributor uses a single 10-pin fat single connector (OBD1 was used 2 distro connectors), black injector clips, dual 02 sensors, an external crank sensor aka ‘CKF’ sensor (a real pain in the ass!), and carried on the grey colored sensor plugs used throughout the engine bay.

OBD2-A Honda/Acura Vehicles

  • 96-98 Civic (US & JDM/UK)
  • 96-97 Delsol (US & JDM/UK)
  • 96-98 CRV (US & JDM/UK)
  • 96-99 Integra (US)
  • 96-01 Integra (JDM)
  • 96-01 Prelude (US & JDM/UK)
  • 96-98 Accord (US & JDM)



In 1999, the next iteration we dubbed OBD2-B took over most Honda/Acura vehicles from 99-01. Though, some Honda vehicles remained OBD2-A such as the USDM 97-01 Prelude.  All 99-00 Civic’s were OBD2-B as were the 00-01 Integra’s. The theft deterrent immobilizer system that was introduced with OBD2-A systems was carried over to certain OBD2-B vehicles such as the 00-01 Integra, but oddly not to the 99-00 Civic line (you’re weird Honda!), S2000, Insight, and other passenger vehicles.

OBD2-B visual indicators are virtually identical to OBD2-A except these few key differences: M/T vehicles use ECU connectors A/B/C (D is blank) – see image below, A/T vehicles use all four onboard ECU connectors, wire harness side ECU connector A is part of the cabin harness and connector B is blue, Non-VTEC Civic’s use an 8-pin small distributor connector while VTEC model EX/Si Civic’s + all Integra’s use a 10-pin fat single distributor connector (same as OBD2A and is backwards compatible with OBD2A vehicles), Integra’s received a digital RPM signal (OBD2A Integra’s were the last of the analog RPM signal).

OBD2-B Honda/Acura Vehicles

  • 99-00 Civic (US & Some JDM)
  • 00-01 Integra (US)
  • 00-09 S2000 (US & JDM/UK)
  • 99-02 Accord (US)
  • 98-02 Accord Euro-R (JDM/UK)
  • Prelude Type-S / S-Type (JDM/UK)



After OBD2-B, here in the US, 2002 ushered in the K-series era vehicles that changed everything. The wiring and ECU system on these cars were technically still under an “OBD2” umbrella just an updated version for the K-series engine and wiring. In the aftermarket scene, a quicky-slang term like OBD2-K was never coined for whatever reasons and still isn’t to this day. TBH, K-series vehicles between 02-11 gets pretty convoluted in differences in wiring and ECU’s. If you’re new to K-series technical mumbo jumbo, its a can of f*ckin worms. Golden Era days were much simpler times!