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Performed on 2001 - 2003 Civic EX & LX models

1. Disconnect the battery negative cable
2. Remove kick plate (three clips).
   Note: Look for vertical ridges moulded into the plastic ( | | | ). Place a flat bladed screwdriver at edge of plastic at each ridge set and gently push forward. A small metal clip, attached to kick plate cover should release. Do all three and pull kick plate down and out. There are two rubber covered pegs along the lower edge which position into brackets for reinstallation.
3. Remove glove box door (2 bolts w/ captive washers along underside of dash, 8mm socket or Philips head screwdriver)
4. Remove dash facia mounting (3 bolts w/ captive washers along underside of dash, 8mm socket or Philips head screwdriver)
5. Remove relay mounting bracket (4 bolts, 8mm socket, easily visible along the lower edge of glove box opening, facing outward. The glove box screws actually mount to this bracket.) Note: the upper right bolt can be hidden from view by the dash fascia, but it is accessible if you crouch lower and look up.
6. Slide the large white/light grey connector (located immediately next to the cabin filter cover) off its plastic securing tab by sliding it down and off.
7. Let relay mounting bracket assembly drop in its entirety. Nothing needs to be removed from it. It will dangle loosely beneath dash.
8. Disconnect ECM connections. Release the tab on the left side of the connector with a flat screwdriver blade and pull out. There are 4 of them, they are colored from top to bottom: White - Black - White - Grey. They are physically keyed in such as way as to ONLY reconnect one way.
   Note: The easiest method to remove is top to bottom as this will give increasing clearance to reach/maneuver the lower connectors. Let connector dangle below dash for replacement ECM testing later on.
9. Remove the bracket mounted to cabin filter and ECM, 2 bolts 10mm socket. This bracket previously had the large white connector mounted, freed at step 6.
10. Remove the two nuts securing the ECM to the firewall. One is top left at firewall, the other is bottom right at firewall.
    Note: a long extension is required to reach nuts.
    Note: nuts are 10mm on a long stud. A deep socket is your best bet, though I was able to remove with a standard depth socket. I had to place the socket on the extension without fully seating it. This gave me enough clearance (over the studs) to break the nuts loose. After a few turns, I pressed forward to fully seat the socket on the extension so as not to loose socket in a tight dark space.
11. Pull ECM forward, making sure to push the various wiring harnesses out of the way. It will be tight about half way out. The ECM will have to rotate slightly counter clockwise and angle at the same time. The Dash facia will need to be pulled outward to give the ECM room. It should be pretty flexible unless your dash is horribly sun damaged and brittle.
    Note: this can only be done with the relay mounting plate (currently dangling down as of step 7) out of the way
12. Installation is pretty much exactly the reverse of this procedure.

Installation Notes

1. Reconnect replacement ECM OUT OF DASH, hanging down like the relay bracket. Reconnect battery and test OBD port for proper ECM communication. Note: one or more of the three relays (Blue, Brown, Black) may also be bad. If OBD communication fails with the replacement ECM, try swapping the relays out one at a time.
2. Disconnect battery before disconnecting the replacement ECM for final installation. Installation is pretty much exactly the reverse of this procedure with a few comments (see what follows)
3. Be sure to visually check the ECM is seated on the firewall studs. I had some issues finding the upper left stud for seating. Nothing terrible, just be aware.
4. Once the ECM is seated on the studs, lightly install the two nuts enough to prevent ECM from falling off the studs. Reattach the bracket removed at step 9, which fits BEHIND the ECM mounting tab and on top of the cabin filter assembly. You may need some wiggle room, which is why the firewall nuts are loosely installed.
5. When the bracket is fully attached and less than finger tightened, then the firewall nuts can be tightened to slightly less then finger tight.
6. Give ECM a wiggle and a forward push to make sure it is fully seated, then cinch all nuts and bolts tight.
7. Reconnect ECM, starting from bottom and moving up.
8. Reconnect battery and retest OBD communication with ECM.
9. Have an automotive locksmith of Honda Tech reprogram keys.
10. Car should start!!!
11. Complete other steps to button everything up.

 
Rep Power: 221

Good write up Stickied

 
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I've pulled mine out two or three times. Every time I hate life, it's such a pain.

 
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thanks, man! I appreciate the sticky! My one wish is that I had the forethought of photo documentation of the process.

 
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The hardest part for me was not having a 10MM deep socket. I got to developed practiced this method enough to have the ECM out in about 15 minutes. It seems like a pain to remove so much stuff, but it does make life significantly easier.

 
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I made it to step 9 and have hit a snag. The 10mm bolt on the filter side came out no problem. The ECM side bolt is stuck stuck. So much so that my driver started to smoke. I'm definitely a beginner in all things car and learning as I encounter new problems, but the general consensus is that I should heat the bolt up. I'm very hesitant to take a blow torch near all those wires and electrical. I'd appreciate any advice or help anyone could give me here.

Also this write up has been a godsend, big gratitude michaelj. All the YouTube videos just skip over the actual removal steps once the glovebox is off, I'd be lost without this post.

 
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You need to get a rachet with an extension. Your driver can be misleading.

 
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What do you mean by the driver can be misleading?

I actually managed to get past step 9 after letting some penetrating oil sit. But now i'm really stuck with step 10, same problem. Both bolts are not coming off even after letting the oil sit.

With these bolts so deep in the space, would a ratchet still be the move? Why would a ratchet work when I couldn't generate enough torque with driver?

 
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You can make more torque than your driver using a long enough lever.

"Give me a lever long enough and a fulcrum on which to place it, and I shall move the world." - Archimedes