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Honda Civic: How to Identify Your ECU

The ECU in your Honda Civic is critical to proper engine performance and efficiency. If you need to fix or replace it, you better be able to identify it first.

By Paul Van Sickle - May 18, 2015

This article applies to the Honda Civic (1992-2000).

A Honda Civic's engine control unit (ECU) is critical for proper engine performance. This component acts as the vehicle's "computer," monitoring a variety of engine sensors and adjusting input parameters to ensure optional performance as well as fuel economy. However, if the check engine light (CEL) on your Civic's instrument panel lights up, the ECU senses a problem with the vehicle and the Diagnostic Trouble Code (DTC) will have to be found to determine the source of the problem. To find the DTC and corresponding problem, you must first determine what On-Board Diagnostic (OBD) scan tool is compatible with your Honda Civic model year. There are two types of scan tools: OBD-i and OBD-II. Read on to locate the ECU and determine the correct OBD scan tool to purchase when diagnosing your Civic.

Materials Needed

  • Phillips screwdriver
  • Ratchet, extension, and metric socket set
  • OBD-i or OBD-II scan tool

Step 1 – Locate the ECU

Disconnect the negative lead (black) from the battery. On all fifth and sixth generation Honda Civics, the ECU is located behind the kick panel in the front passenger's side foot well. To remove the ECU and view its bar code label, use a ratchet and socket to unbolt it from the sidewall. Disconnect the wire harnesses of the ECU before completely removing it.

Figure 1. Honda Civic's ECU location.

Step 2 – Identify the ECU type

Look on the side of the ECU to view its bar code label. This label contains the part number, which indicates what transmission, engine, and OBD scan tool the ECU is compatible with.

  • All fifth and sixth generation Civic ECUs begin with a five digit number: 37820.
  • The following three-digit alphanumeric code determines the ECU engine compatibility (e.g., P28).
  • The third three-digit alphanumeric code determines the ECU transmission compatibility (e.g., A02).
  • The nine-digit number below the codes represents the module number: 760-784373.

The code you are most concerned with is the middle three-digit alphanumeric code (refer to Figure 2). Here's a list of which OBD scan tool is compatible with each Honda Civic model year:

  • P05: '92-'95 OBD-I Civic CX
  • P06: '92-'95 OBD-I Civic DX
  • P07: '92-'95 OBD-I Civic VX
  • P08: '92-'95 OBD-I Civic D15 JDM
  • P28: '92-'95 OBD-I Civic Si/EX
  • P2N: '96+ OBD-II Civic HX Coupe
  • P2P: '96+ OBD-II Civic EX Coupe
  • P2E: '96+ OBD-II Civic DX Coupe
  • P2M: '96+ OBD-II NZ Civic SOHC VTEC
  • P2T: '99+ OBD-II Civic Si Coupe

Figure 2. Honda Civic Si/EX 1992-1995 OBD-I.

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