imtrouble

Just recently had a engine melt down, i have a 2001 civic ex coupe (Si in canada), anyways had to put a used engine in, the used engine was out of a 2004 civic ex (Si), anyways since then the check engine light has been on for the upstream o2 sensor, we replaced it and the same thing. i researched the problem and found that the 2001 to 2003 civics had 2 o2 sensors, but on the 2004 it was switched to a air/fuel ratio ratio sensor. The engine wiring came with the new engine. so what do i have to change in the wiring to correct this. The other way is to replace the sensor and ecu i assume, so rewiring the upstream o2 is easiest?

ezone

So you already swapped the old primary O2 sensor back into the new engine, and it still doesn't work right?


What is the exact code?
New sensor? Where did the O2 sensor come from? Is it OEM or Bosch?

At the primary O2 connector, the 04 harness has wire colors of:
Red/Yellow
Green/Yellow
Red
White

Does this match so far?


Unplug the primary O2 sensor, turn the ignition key to RUN (but don't start it)

Is there battery voltage on the white wire of the engine harness? (NOT the white from the O2 sensor)
If it has the 12v, it LOOKS LIKE all should work as long as the sensor is actually good.
If no, then check fuse #4 in the dash fusebox.. (I'm only looking at a diagram, I can't see or check the car to verify what is or isn't.)
(If the fuse is good but there is no hot at the white wire, that might be the issue. Holler back on this.)

As long as you didn't mess with the wire terminal positions in the O2 sensor connectors, it looks like this white wire is the only difference between the two. The sensor should plug in and work if it will actually plug in.
NONE of the wire colors are supposed to line up between the sensor and its harness though.

Oh yeah, is this a manual trans or automatic? IDK if it changes anything in the diagrams.

HTH?

imtrouble

the code is p0135

yes we put the original o2 back. the guys in my shop checked all the connectors and wiring and all looks good.

when they did the engine swap the 2004 wiring harness was used, since the 2004 uses a air/fuel ratio sensor instead of the primary o2 i assume i just need to find out where the difference is at the ecu for the o2 sensor and the air fuel ratio sensor. I think i just need to find the difference and change the pin locations

btw it is a 5 spd

ezone

Do check the rest of the stuff mentioned in my last post

ezone

Get a good wiring diagram. Here's the differences I see right now using a book instead of web based diagrams:


The "sensor ground" wire (red/yel) needs moved from location A16 to A10 at the PCM connector.
(Is there already something in that hole?)


Terminal A22 (wht) needs disconnected at the PCM and rewired to receive B+ from fuse #4 in the dash fusebox terminal D3
I think this one can be done within the harness junction connectors. Again, get a GOOD diagram to find it.
This wire used to go to the AFS Heater relay, which the early car does not have.

imtrouble

Thanks ezone

ezone

One more note: I'm using USA diagram book, I can only hope the Canadian version is the same as far as engine controls go.

04 Honda Civic

iTrader: (2)

I am not 100% sure about this, but I believe only 04-05 had heated O2 sensors.

Maybe that is something to look into?

Edit:Looks like Ezone knows what to do..haha

ezone

You're thinking of A/F sensor vs O2 sensor in the primary hole.

All have used (internally) heated sensors for ages now. All of the sensors that have 3 or more wires is heated.
A single wire sensor is not heated internally. I'm thinking those haven't been used since OBD2 began, if not before that.

Yeah I think it's easy, but it's just hard to explain. That's why OP needs his own wiring diagrams.

04 Honda Civic

iTrader: (2)

Ah my mistake, I knew they were different one way or another.

So the difference is Air fuel sensor vs regular O2 sensor?

imtrouble

Yrs mine has the primary o2 there and the ecu expects it there, but the wiring harness that came with the motor is wired to have the air/fuel ratio sensor there, but if i were to put that sensor there my ecu wouldnt read it. i just need to change/move the pin connectors so my ecu can read the o2 correctly. my techs can look up the wiring diagrams on mitchell on demand, but since they dont have honda experience i am hoping you guys can help. I have given ezones comments to my techs and they are looking over them

jcb111

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. Not 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)