I have a 99 DX Civic hatchback that I converted to manual. Everything works wonderfully. I have heard that if you get the ECU off a manual that you can fix the check engine light that comes on when doing this conversion.

My ECU is this one a small square looking one marked P2E that uses all four ports on the ECU



I went to the junk and found a 4 door LX that was manual. Its also marked P2E but this one is a longer rectangle type and also only uses 3 of the four ports available on the ECU so won't let me car turn on





Is it because this one is off an LX that it doesn't use the 4 ports. Im confused on why this would matter. What ECU do I need to get. Does it have to be EXACTLY off a Manual DX for it to work on my DX hatch?

Please help !

 

You likely have a version type problem. You will need a DX/LX ECU from a '99-00 manual Civic to eliminate the eternal CEL for automatic trans related codes. What you have likely done is sourced a '96-98 P2E ECU and the ECU plugs at your engine/chassis harness connect at different locations. This creates the "No Start" situation that you are experiencing.

Just find a P2E Manual ECU from a '99-00 Civic. Your engine harness has 3 plugs and your under-dash harness has a fourth one... and all four are used with an automatic transmission application. When you convert to a manual transmission, only three plugs will be connected to the ECU (not four): two plugs from the engine harness and the single plug from the under-dash harness. The remaining engine harness plug is for automatic transmission sensors and control... and you don't have that trans anymore.

 

ok so you think / know that its because I got the P2E from a 96-98 spec instead of 99-00.

I thought so too because I was reading about ODB2A or B and the 99-00 is B.

So when If get the 99-00 DX / LX Manual P2E ecu I will only plug in three of them and leave one out because that's automatic stuff.

Am I getting that correctly lol ?

Thanks for the detailed explanation. I just wanted some more confirmation so I don't feel bad about buying one if need be.

 

Absolutely correct. I am assuming in this, as well as my previous post, that you are using the original engine harness that came with the car. If not, please post what engine harness you have converted to so that a proper path forward can be assessed for you.

 

Yes I have the original harness in the 99 Honda Civic DX hatchback. I found one on eBay and I asked him to send me a photo of the ports.

I see one doesn't have any pins on them. Is this the one from my car that's blue colored that I will leave unplugged. Im providing a photo that he sent me.

Don't mean to be a paint but im feel im almost there lol. If this will work im buying it asap.

its the smaller size. Its missing a whole set of PINS and he says its a manual and from a 99 maybe this is a winner

 

Your pictures are terrible... let's clear up two important details: First, if the part number is 37820-P2E-A0X, it will be a DX/LX manual ECU. Second, if you hold it with the part number readable and the ECU plug locking tabs facing up, the open plug location should be found at the FAR RIGHT side. All of the plugs that will be plugged into it will be in a solid row beginning at the left. Two will be from your engine harness and the last one will be the one found under the dash of your car.

Your top pic above looks like the ECU is upside down and the bottom pic is small enough and far away enough that I cannot read the part number.

If you can confirm that both items I have listed above are as I have indicated... buy it.

 

Yeah im not sure why the photos compressed so badly. Either way yes you're right one port all the way to the right is empty or "open"

The part number is 37820-P2E-A12 and there is another set of numbers under it that reads BIG 59 then 1200-208728

im also finding online that ending in A12 can be DX/CX or LX

think I got a winner ?

 

Found this site and under vehicle fitment it shows 1999 DX 3 door.

https://www.hondapartsnow.com/genuin...0-p2e-a12.html

 

I think you found a winner.