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To identify your ECU you will need to know its generation, part number and possibly its ROM number.

The ECU can be located in several places: under a metal plate in the passenger's footwell (models up to 91), in the passenger's footwell behind a plastic panel (models 92-99) or by the driver's footwell under a plastic panel (some models 2000+)

The computer is connected via three connectors that pull out when a plastic clip is pressed. Remove the computer, and with a philips screwdriver remove the metal lid from the top of the computer. There may be small daughter circuit board covering some of the main circuitry. Unscrew this and lift it out of the way.

All Honda ECUs have a part number which is located on the side of the ECU and inside the ECU on the connector. e.g. 37820-P72-A01

The part number consists of three components:

• Honda's part number for ECU, which is always 37820
• Three characters (which are loosely related to the model of car/engine). e.g P72
• Three characters (which are the revision of the ECU) e.g. A01

in 88-91 ecus (PM6, PR4, PW0, PR3, PM7):

• 5spd = 000, 001, 002, A00, A01, A10, J00, J001, C01, C00
• Auto = J51, J50, A50, A51, 901, A60, C50, C51, X30, A80, L50, L51

92-95 ECUs (P28, P30, P61, P72, P91, P08)

• 5spd = 000, 001, 002, 003, 004, A00, A01, A02, C00, C01, C02, J00, J01, J02, G00, G01
• Auto = J50, J51, 901, 902, C50, C51, C52, A50, A51, A52, L50, L51, G51

96-00 ECUs (P2E, P2P, P2J, P72, P73):

• 5spd = 000, 001, 002, 003, A00, A01, A03, C00, C01, C02, C03, J00, J01, J02, A11, C11
• Auto = A70, A71, A72, A91, A92, C70, C71, C72, C91, C92

From the patterns we can learn the following:

• first letter = country of orgin
• J = Japan
• C = Canada
• A = USA
• G = Europe
• The second digit, if 5, 7, 9 then ecu is auto usually
• The third digit denotes the version/variation
• L = California emissions or typically high altitude states as well.

The middle three characters are the most useful to identify what the ECU is. Different generation ECUs may use the same characters. e.g. a P72 OBD I ECU is different from a P72 OBD II ECU. Here is a list of common ECUs:

• PG7 : 86-89 Integra (86-87 vac advance, 88-89 electronic advance)
• PM5 : 88-91 Civic/CRX DX
• PM6 : 88-91 Civic/CRX SOHC Si
• PM7 : 89-91 DOHC ZC (JDM 'EF' ECU)
• PM8 : 88-91 CRX HF
• PR2 : 89-91 ZC (Euro)
• PR3 : 89-91 JDM B16A EF8/9
• PR3-J00 or J51 : 92 JDM Integra B16A EF8/9
• PW0 : 89-91 JDM B16A EF8/9 DA6-XSi
• PR4 : 90-91 Integra LS/GS
• PS9 : 88-91 4 door Civic EX Auto
• P05 : 92-95 OBD-1 Civic CX
• P06 : 92-95 OBD-1 Civic DX
• P07 : 92-95 OBD-1 Civic VX
• P08 : 92-95 OBD-1 Civic D15 JDM
• P0A : 94-95 OBD-1 Accord EX
• P13 : 93-95 OBD-1 Prelude Vtec
• P0F : 92-95 OBD-1 UKDM Accord H22
• P14 : 93-95 OBD-1 Prelude Si (non Vtec)
• P27 : 92-95 OBD-1 EG JDM Civic 1600 sohc
• P28 : 92-95 OBD-1 Civic Si/Ex
• P30 : 92-95 OBD-1 DelSol DOHC Vtec Si/EG SiR
• P54-G31 : 1997 Honda Accord 1.8 LS
• P61 : 92-93 OBD-1 Integra GSR
• P72 : 94-95 OBD-1 Integra GSR
• P72 : 96-00 OBD-2 Integra GSR
• P73 : 96-00 OBD-2 Integra Type-R (JDM & USDM)
• P74/75: 92-95 OBD-1 Integra LS/GS
• P75 : 96-00 OBD-2 Integra LS/GS
• P2N : 96+ OBD-2 Civic HX Coupe
• P2P : 96+ OBD-2 Civic EX Coupe
• P2E : 96+ OBD-2 Civic DX Coupe
• P2M : 96+ OBD-2 NZ Civic SOHC VTEC
• P2T : 99+ OBD-? Civic Si Coupe
• P5P : 97-00 OBD-2 Prelude Type-S (JDM ECU)
• PBA : 97+ US Acura 1.6EL
• PCT : 98+ JDM ITR / CTR
• PCX : 99+ OBD-? S2000

As further identification Honda ECUs have a software revision number inside the ECU. This is usually a two or three digit number stamped on the 28 pin ROM, or main processor. Accord and Prelude ECUs can use a letter and number code.

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