swaggs21

I am a member of HAN, but I thought that you all might be able to help me out too since I haven't gotten an exact response from anyone over there on this problem.

Westcoast and I have been battling a problem for about 2 months that you all maybe to help me with. I asked before, but I want to poll you all one more time to see if I can get a better result.

I am battling an O2 Sensor problem, but it isn't the O2 Sensor, already checked that.... So today we took the ECU out of a 99 Civic EX (Just like mine, made 14 days before), and put it into my car. It threw a code, but this time it was a 1 instead of a 41 (1 is O2A - Oxygen sensor #1, 41 is Primary oxygen sensor heater).

So my question is this. Why would two identical ECU's throw two different codes, and is this telling me anything that is not blaringly obvious to me or Westcoast?

Now at least I know that the ECU is not bad, which is a sigh of relief, but could a dirty intake manifold, CAI, or header cause this? I have had an aftermarket CAI and Header on this car for about 50k before this code came up, and since I am putting on a turbo in a couple of weeks, I don't want to be running really, really rich. I am thinking it is something dirty or the wiring harness, and I really don't want to have to pull the wiring harness.....

If anyone has any ideas let me know.

EE_Chris

With a multi-meter you can check the heater resistance (15-40ohms) and also check for shorts and opens in your wiring. If your resistance measurements check out, then your probably looking a new O2. How many miles are on this O2?

swaggs21

There are about 4k miles on this O2.

I will give you the background.

I started throwing a code driving home from WV, so I checked it when I got home and it showed me a 41, so I went ahead and bought a new O2 Sensor and put it in, cleared the ECU, and started the car. Code came up again. So then I took the new O2 Sensor and put it into another 99 civic, started it up, no codes, so this tells me the sensor wasn't bad. Next we took the ECU's and swapped them, but got a 1 code instead of a 41, and the ECU's are the same year (made only a couple days apart). So now I know it is not the ECU and it is not the O2 Sensor. The one odd thing though is in my ECU, the 41 code came up within 5 seconds of starting the car. With the swapped ECU, it came up after I went out and drove the car for about 5 minutes and came up with the 1 code.

I also put a volt meter on the wires to the ECU from the O2, and got the correct reading, and then checked the wires in the O2, and once again got a good reading.

So this is where I asked you all the question above. Could it be sediment from the air and fuel in the intake manifold or header causing this?? Maybe build up on another sensor?

What did you mean by heater resistance?? I am not familiar with that term.

I dont want to have to pull the wiring harness out, but if I have to I will. Any other opinions are welcome.

2lua

sounded like your o2 not plug in tight. my friend had the same problem when he swaped out the o2 and it did not plug in tight and it kept throw he 41 and 1 code, until he put it on the lift, i was helping him check out the o2 problem, the plug was loose, but it still lock at the metal clip holder.

swaggs21

I will look at that in the morning, but I am pretty sure that we checked all that.... If not, I am really going to kick myself.

swaggs21

I will look at that in the morning, but I am pretty sure that we checked all that.... If not, I am really going to kick myself.

swaggs21

Oh ok, I just wasn't familiar with the term.

Yeah, and it checked out fine, that is why we think that it is comething else other than the O2 sensor that is causing it.

I can't use IM yet for some reason, so I had to post my response here...

Thanks for all the help, I appreciate it!!

swaggs21

Oh ok, I just wasn't familiar with the term.

Yeah, and it checked out fine, that is why we think that it is comething else other than the O2 sensor that is causing it.

I can't use IM yet for some reason, so I had to post my response here...

Thanks for all the help, I appreciate it!!