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Identifying your ECU

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.

ECU Generations

Honda ECUs run in generations, which use different connectors.  Below is a stack of ECUs running from the newest generation at the top to the oldest generation at the bottom.


OBD2B (left 3 plugs used)

OBD2A ECU

OBD1 ECU

OBD0 (JDM PR3 and PWO)

ECU Part Numbers

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 or G52

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: 

The last 3 characters are broken down into 3 parts. "A" generally is used for US ECUs. "G" is European, and "J" is Japanese. There are other versions of this, but you get the idea. The second digit "0" typically means manual transmission, where a "5" means automatic transmission, and the last digit "1" is the version number.  

  • 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 Civic EX 4 door Auto
  • P05 : 92-95 Civic CX OBD1
  • P06 : 92-95 Civic DX OBD1
  • P07 : 92-95 Civic VX OBD1
  • P08 : 92-95 Civic D15 JDM OBD1
  • P0A : 94-95 Accord EX OBD1
  • P13 : 93-95 Prelude Vtec OBD1
  • P14 : 93-95 Prelude Si (non Vtec) OBD1
  • P27 : 92-95 EG JDM Civic 1600 sohc OBD1
  • P28 : 92-95 Civic Si/Ex OBD1
  • P30 : 92-95 DelSol DOHC Vtec Si/EG SiR OBD1
  • P54-G31 : 1997 Honda Accord 1.8 LS
  • P61 : 92-93 Integra GSR OBD1
  • P72 : 94-95 Integra GSR OBD1
  • P72 : 96-00 Integra GSR OBD2
  • P73 : 96-00 Integra Type-R OBD2 (JDM & USDM)
  • P74/75: 92-95 Integra LS/GS OBD1
  • P75 : 96-00 Integra LS/GS OBD2
  • P2N : 96+ Civic HX Coupe OBD2
  • P2P : 96+ Civic EX Coupe OBD2
  • P2E : 96+ Civic DX Coupe OBD2
  • P2M : 96+ Civic SOHC VTEC OBD-2 NZ
  • P2T : 99+ Civic Si Coupe OBD?
  • P5P : 97-00 Prelude Type-S OBD2 (JDM)
  • PBA : 97+ Acura 1.6EL US
  • PCT : 98+ ITR / CTR JDM
  • PCX : 99+ S2000 OBD?
2002-2006 (K-Series)
  • PRB (A01-A12 & 305) : 02-04 RSX Type-S OBD2 (white plug) (USDM)
  • PRB (A13-A16) : 05-06 RSX Type-S OBD2 (white plug) (USDM)
  • PND : 02-04 RSX Base OBD2 (white plug) (USDM)
  • PNF : 02-04 Civic SI OBD2 (white plug) (USDM)
  • PRA : 02-04 Euro Civic Type R OBD2 (white plug) (UK)
  • PRC : 02-04 Integra Type R OBD2 (white plug) (JDM)
  • PRD : 02-04 Civic Type R OBD2 (white plug) (JDM)
  • PPA : 02-04 CRVOBD2 (white plug) (USDM)

You can only reflash ECUs with a working ECU/immobilizer/key combination. Because of this you cannot reflash PRA, PRC, PRD or PPA ECUs.

Notes:

  1. If this ECU is used with a 6 speed transmission, reverse lockout will not work.
  2. PND A5# can be used only with Automatic transmissions and only reflash programs are available for this ECU.
  3. Use of this ECU is only recommended for motor swaps, because no one offers any programs for the CRV.
  4. This ECU does not use a wideband oxygen sensor and is not compatible with US or JDM vehicles.
  5. Only Manual ECU's can be used with the Hondata K-Pro
  6. PRB-A13 ECU's are not reflashable or Hondata K-Pro compatible (2005 RSX).
  7. Nitrous features will not work with this ECU.

ECU ROM Numbers

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.