AaronpKC

I've owned this car for over a year now and have put just over 10k miles on it. My CEL has never been on, though my ultragauge has always told me P1298 (load detector) was being thrown. Well yesterday my CEL came on and threw a P1167 code. I haven't checked the ohms yet or the fuse associated with it (15 I think?) but I noticed my o2 is only 4 wire (2 blk, 1 wht, 1 grn) and the connector off the engine harness is only 4 wires (1 red, 1 red w/ yellow, and two others) as we'll not 8or7. I believe my carfax says the vin is for a manual car.

I found this on another forum:
P0135/P0141 indicates that you have the 4-wire sensor. You would get P1166/P1167 for a 7-wire sensor.
That being the case, does this indicate my ecu is the right one (for a manual) then how did I go this long on a 4wire before throwing the CEL?

My question is which sensor do I have and what do I need to replace/fix it.

I've always thought my car got less mpg then it should (ultragauge says avg 29.9 when my driving is 70% hwy at 70 mph). Today my car ran in open loop the entire time (but ran better though :-P)

darcane

I have nearly the same, if not an identical car. Mine is originally from California, so it is a little different than the 49-state cars. This thread shows which O2 sensor I bought, and I have had no trouble with it since. I picked it up off Amazon.
https://honda-tech.com/forums/honda-civic-2001-2005-78/01-civic-hx-3155104/
I just checked, mine has only four wires.

One problem with the ultragauge is that it is unable to determine the fuel usage when running in lean burn, and it will calculate higher than actual fuel consumption. You can check when it is lean burn by monitoring the last O2 sensor (It's called "Bank1 O2 3" on my car), when it drops to 0.00, it is in lean burn mode. You can feel it stumble a little when it switches over if you really pay attention.

Under 30mpg is really low for an HX. Did you calibrate the Ultragauge? What do you get when you calculate by hand? If it doesn't come up quite a bit with the O2 sensor, you may look and see if other maintenance needs to be done, spark plugs, clogged EGR, tire pressure, etc.

Driving habits matter a lot, but my worst tank so far was still 40mpg...

lazlong

My EX would get 30+ mpg @80 mph with the A/C on. HX should get even better mpg.

AaronpKC

Thanks @darcane for the responses. Also, thanks for the hint on identifying lean burn with the ultragauge. No, i have not calibrated in regards to distance. I have the "fuellog" app for android and its saying my last 3 tanks are 35.31,33.67, and 34.25. Before that they all were around 32 on winter fuel in the midwest. My driving habit isn't aggressive at all, nor is it granny like either. Most of my driving is on the hwy with cruise control. I've always thought that when a/c was on my car had better power and fuel economy, weird right, so i thought maybe my lean burn was messed up thus causing worse gas mileage. Now that the o2 is malfunctioning and my car is running in open loop i can tell it has better power and my avg mpg on the ultraguage even rose today! My tires are all at 35psi and I'm running full synthetic oil. Oh, another important note is that while i was working underneath my car one day I found out the transmission
had been replaced before I bought it by the blue writings "04 civic lx" so my rpms are a bit higher at 70mph than where they should be.
I haven't gotten around to it yet being busy with school and work, but I was planning on doing an in depth tune up based off this write up:
http://www.civicforums.com/forums/11...e-up-mods.html

I'm going to check the fuse commonly referenced in o2 threads, then order part #13680.

Anyone know why we have the 4 wire and not 5 wire o2 sensors? My hood was replaced so I don't have the label detailing the engine information.

-Aaron

darcane

Definitely calibrate the ultragauge, both for distance and fuel use, and it will give better information. It will still be off due to lean-burn though, so just be aware of that.

A/C may kick you out of lean burn, which would increase power. It should not improve economy though.

That LX tranny isn't helping, if that is what you have. You can look up the code on the bell housing to verify what it came from. The good news is that you probably don't have to worry about tranny problems for a while...

No idea why it's a 4-wire instead of 5. It works, I don't worry about it.