Rep Power: 0

I recently swapped my D17A1 out of my 2005 Civic LX SE with a D17A2. I had the Motor, Trans, Wire harness and ECU from the donor 2003 EX. The motor is in and running on the stock LX ECU right now throwing the code for the 2nd O2 sensor, and no VTEC. I have an appt at Honda on Wednesday to have the ECU flashed to match my keys so I can get the VTEC working.

So in the mean time I have been searching all the forums for how to wire in the 2nd O2 sensor as the factory harness does not have it on it like on my LX. As I have read on all the forums the 2nd O2 sensor is part of the body harness. I dissected the harness from my old motor to get the wires for the O2 sensor. I have put the pins into the connector at the ECU where they were on the LX.
pin 25 wht/red Secondary O2
23 brn/yel Logic Ground
14 blk/wht SecondaryO2 sensor heater control
10 grn/yel Sensor ground

The last wire is Black/Yellow and I can't figure out where this wire goes. I think it would be pins 2 or 3 which are supposed to be yel/blk power source but not sure so I left it disconnected.

Checked for codes and now I have 8 with all these connected. It throws a code for both O2 sensors. When I take the Logic ground off it only throws the secondary O2 and heater code. So I tried the Logic ground on pin 24 which is also supposed to be logic ground with the same result, throwing 8 codes.

Am I having these issues because I am running on the LX ECU and did not flash the EX ECU yet?

The O2 sensors are new and for the EX motor not my LX O2 sensors, still using LX ECU at the moment.

I replaced the whole exhaust headers back with aftermarket, 1 O2 Sensor at bottom of header the other is about mid car under the console. No CAT installed, but 2nd O2 is with spacer.

Where do I wire in the 2nd O2 Sensor at the ECU?
There are 4 wires and a shield

Not that it matters but also replaced while the motor was out
Timing Belt, Water Pump, Thermostat, Crank Seal, Cam Seal, Valve Cover Gasket, Both Belts, Spark Plug Seals, Output Shaft Seals, Clutch Kit, Motor Mounts, O2 Sensors, Full Exhaust, Cold Air Intake, All Fluids

Please Help if you can, I am not your average everyday idiot. I am a Tech by trade and have worked on cars for years. I have owned this car since new and haven't ever had to do anything but the usual maintenance. Haven't done a swap since the early 90's. I also have all the tools and testing equipment at my disposal.
Thanks Again for all your help
Jason (n00b)

 
Rep Power: 0

Thanks for all the help.
Since no one wanted to assist me on my shitty daily driver thought I would ad the info in as I have made it all work

All good after flash from Honda
Keys work now with the ECU that matches the motor
Only code its throwing was the heater on O2 sensor 2
Wired the Black/Yellow wire to pin 5 yel/blu on connector E
Wired all O2 stuff to connector E and all good now, No codes

So just so its cleared up for anyone else doing a LX - EX conversion in a 2001-2005 Civic here is where the wires are landed when using EX Motor, Trans, Wire Harness and ECU

Here is where they are on the stock harness Connector A (31 pins)
25 wht/red Secondary O2
23 brn/yel Logic Ground
14 blk/wht SecondaryO2 sensor heater control
10 grn/yel Sensor ground
Blk/yel Heater acc power

Here is where they go on Connector E (31 pins)

2 wht/red Secondary O2
3 brn/yel Logic Ground (Shield from O2 Sensor)
5 yel/blu Sensor voltage (attach to blk/yel from O2 Sensor)
6 blk/wht SecondaryO2 sensor heater control
Connector A (31 pin)
10 grn/yel Sensor ground

On the wht/red and Blk/wht
I dissected the old harness to get the whole wire with the metal ends that fit into the harness. As you will find out when going from LX to EX there are a few different wires and they are not in both body harnesses the same way. On the other wires I just tapped in and soldered and taped as not to cut the factory wiring.
I hope his helps anyone that might be doing the same swap that I needed to do to get my everyday driver back on the road with a few upgrades.

 
Rep Power: 0

Hey pleas tell me you have a video on this, i need to do this to my car and you are the only post i found to do this. I have the pigtails for my downstream sensor got from a junk yard.

 
Rep Power: 0

Sorry man no video.

I didn't even take pictures of the process because I wasn't sure it would even work haha

The instructions are pretty detailed as far as where and what to connect to the ECU

Your down stream wire colors will differ from the ones I have listed. They will connect into the same place though.
2 wht/red Secondary O2
3 brn/yel Logic Ground (Shield from O2 Sensor)
5 yel/blu Sensor voltage (attach to blk/yel from O2 Sensor) <---your colors are different than blk/yel
6 blk/wht SecondaryO2 sensor heater control
Connector A (31 pin)
10 grn/yel Sensor ground

You can google the ECU connectors and look at those to verify you are using the right connectors

You might have to put a meter on the OBD2 sensor to figure out that wire is what.

I did this when no one else had a good listing on how to do this and all my info came from this group or honda pin outs to figure out placement and functionality.

Hope this helps

 
Rep Power: 0

Here is the other threat that has a few other questions answered on it

https://www.civicforums.com/forums/3...vtec-swap.html

 
Rep Power: 0

Any chance you guys are still around on this? I am attempting to do this, but I am not having any luck. 2 of the pins listed are in use on my harness.. and it has left me stumped with what to do now.

 
Rep Power: 0

I can try and help.
Sold the car and don't have anything for reference
I am amusing you have a LX Car and are installing and EX"Vtech" motor in.
That's what I had
Also had both harnesses, the one from the LX motor I removed with the motor and the EX harness with the donor motor.

 
Rep Power: 0

i know this is old, but I just did the same job, I used the connector from the lx harness to make a pigtail from the secondary 02 but my issue is where is the brown yellow wire I’ve found all the others and wired up, but I’m lost on the logic ground wire. Any ideas on what I’m doing wrong?

 
Rep Power: 0

Here is where they go on Connector E (31 pins)

2 wht/red Secondary O2
3 brn/yel Logic Ground (Shield from O2 Sensor)
5 yel/blu Sensor voltage (attach to blk/yel from O2 Sensor)
6 blk/wht SecondaryO2 sensor heater control
Connector A (31 pin)
10 grn/yel Sensor ground

Honestly this was so long ago I forget.
Looks like connector E Pin 3 is Brown/Yellow connects to the shield from O2

Hopefully this helps

 
Rep Power: 0

thank you this helps! I didn’t know which was the the shield 02

 
Rep Power: 0

this seems like the best place to ask
P0137 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2 looking to buy wires to rewire my male o2 sensor connector for bank 1 sensor 2 back into the engine wire harness on my 2001 honda civic ex manual sedan. I have tried splicing the wires back together but still no fix. My plan is to trace all the wires back to the ecu and replace them and hope that solves my issues