Jacinto,

Download the helm manual already! You are asking very basic questions and the answers are in the pdf. You've got broadband, don't you?

I will read this thread for a while longer because I enjoy the entertainment. You newbies (and you should know who you are) don't seem to have a clue how to work on a car and shouldn't be doing so in the first place. There, I said it. I feel better now.

That page needs a slight correction... LAF = Linear Air Fuel sensor, not Lean. The 5-wire O2 sensor IS the Linear Air Fuel sensor, not just part of it.
The Helm's manual (Helm, Inc. reprints the Honda workshop manuals) pretty much says to reset the ECU (I'll get to that in a sec) and turn the ignition on. If the CEL comes on immediately with a code 48, check for shorts or breaks in the wiring. If no code comes up, take the car for a test drive. If the code pops up again during the drive, check for breaks in the wiring between the sensor and ECU. If the wiring checks out, replace the sensor.
Resetting the ECU is pretty easy... Switch the ignition off, pop the hood and take a look at the fuse box under there. Remove the fuse for the hazard lights (aka 4-way flashers) from it's socket for 5 seconds and then plug it back in. Done. Close things up and go for a drive.

Checking wiring can be kinda confusing. Actually doing the checks is easy, but figuring out exactly which wire you're supposed to be checking can be tough. You need a multi-meter with a continuity check function and long (long enough to reach from the passenger footwell to the LAF electrical connector) test leads.

Looking at the wiring harness side of the LAF connector, you'll see 7 wires. As I understand it, two of those wires connect to a calibration resistor in the
sensor's side of the connector... That's why you only see 5 actually running down to the sensor itself. Anyway, those 7 wires run back to 7 terminals in the ECU electrical connectors.

A little preparation... You'll have to unbolt the ECU from the side of the passenger's foot well to reach it's electrical connectors. You can probably get away with just leaving the ignition off while testing, but if you want to be extra safe, disconnect the negative battery terminal.

Ok, actual testing: You're going to disconnect the LAF and ECU connectors and then touch one multimeter test lead to the appropriate terminal of each to make sure the length of wire between the two isn't broken. The meter should beep if the connection is good.
If the wire checks out, it's a good idea to then do a similar test between one of those terminals (it doesn't matter which - they're connected, right?) and body ground. That simply checks that the wire isn't shorted out somewhere.

Body ground is simply the car body. The body is made of steel, which is conductive. The negative terminal of the battery is connected to the body as well, so body ground is simply an easy return path to the battery for most of the car's electrical components... Like a giant wire. Anything conductive (metal) that's directly bolted to the body or engine (including most solid black wires - NOT black with a colored stripe - you'll find around the car) is therefore connected to the battery's negative terminal.
If you want to use some random metal object as a ground connection, make sure it isn't painted. Paint is generally non-conductive, so you won't get a connection to ground by simply touching the meter probe to the paint.

Back to testing: The ECU connectors are each assigned a letter. The pins in each of those connectors are then numbered. Connector A is the largest with 26 pins - 2 rows of 13. Before you unplug the connectors from the ECU, orient it so connector A is on your left. The pins are numbered top to bottom, progressing to the right. That is, the top left-most pin is #1, the pin immediately under it is #2, the pin to the right of 1 is #3, the pin under 3 is #4, to the right of 3 is #5, #6 is below 5 and so on. So you'll have all the odd numbered pins in the top row, and the evens in the bottom row. Some pins are a slightly different size than the others, but it shouldn't be enough to upset the numbering scheme. Some positions in the connectors will be empty - there won't be a pin or wire there, but one could be plugged in... Don't skip them. Count the empty positions as if there were a wire there.
To the right of Connector A is Connector B. It's the smallest with two rows of 8 pins, 16 in all. Connector C is skipped in most Civics for some reason... I guess they didn't need the wiring capacity. So that leaves the right-most connector - D. D should have two rows of 11 pins, 22 in all.
If you look closely at the ECU connectors, they should have a molded-in cover snapped down over the rows of pins. If you release that cover (it's got a little snap-clip thing at each end), you can touch each pin from the wire side, known as back-probing.

And now for the actual work. Oh, wires are identified by their color... The color of the wire's insulation (the casing around the bare wire) followed by the color of the stripe on the casing, if it has one. The first wire - yel/blk is yellow with a black stripe.
I'm going to list these as the color of the wire at the LAF connector, followed by the ECU pin. The colors may be the same at the ECU, but some color combinations are re-used, and sometimes the colors change going from one wiring harness to the next, so it's better to figure it out by the pin number and just consider it confirmation if the color combination is the same at the ECU.

yel/blk to pin A6
blk to pin A23
wht to pin D3
wht/blu to pin D8
orn/blu to pin D14
orn to pin D16
grn/wht to pin D22

Happy wire prodding. :)

!! What is the silicon boot of the o2 sensor!?!? !!

I love you guys. :)

https://bp0.blogger.com/_Y8WoJeZ-J4c/...+o2+sensor.jpg The white plastic piece is not the silicon boot of the o2 sensor is it?

That looks like nylon to me... It's just covering the threads.

so the mechanic was supposed to remove that before installing, right?

Goodbye, cruel world!

EEEEEEYYYYYYAAAAAAAAAAHHHHH!!! :)

haha, I think I'm hopeless

I Agree with you on the last part, but I didn't see myself using the o2 sensor socket more than once, so I figured paying the mechanic $15 to do it with his (which he didn't have) would be cheaper than buying one for $40 (which is how much the thing cost locally) Anyway, sorry for seeming unappreciative, I'm upset because I know there is someone out there who could get this working right, but mechanics have zero interest in having me be a customer of theirs on my terms (me bringing them the part, having them install it without cutting the wires and without throwing the parts away) they are so stuck in their mode of working that they can't be bothered to changing how they do things for one individual. I don't have the time and patience to take matters into my own hands. Tomorrow morning I'm gonna attempt the ECU replacement as that seems relatively easy and straightforward. (Plug and play, right?) Forgive me for being a brute.

Sorry, but this is the truth.

I went from knowing nothing about Hondas a little over 5 years ago, to now being able to do a motor swap in under a few hours.... I read the Honda paper manual I had all the way through, and read countless online ones just to get a basic knowledge I needed before even touching the cars. (And cars are just a hobby and part-time job for me, not a career.) This is a first step you really must take or you will be consistently ripped-off by every mechanic you go to. Owning an older car and not being car-smart is a bad bad bad idea....even if it is a Honda. :(

I have six cars. If I took them all to a mechanic, I wouldn't be able to afford keeping/maintaining and modding them.

ECU is pretty much plug and play. If you are mechanically inclined, I don't think you will have a problem removing and installing a new ECU. The hardest part is probably pulling the connectors from the ECU as they are locked.

If you don't have the right tools, simple removal and install of components end up being a major task. Through the years, I've bought so many tools I'd say I spent a few grands... everytime I work on my car, I usually have the right tools and it's such a satisfying feeling to be able to fix your own car and save hundreds (if not thousands) of dollar. I even make money doing this on the side. A friend told me Lexus was going to charge her close to $2k to change the timing belt and a few other things. I told her I'll do it for half and made a few hundred bucks. I'm so car crazy I even bought a four post car lift! My family think I'm a bit overboard ...

When I bought the VX, they really thought I went crazy, but after gas went over $3.50 (this is CA) gallon last year, they realize I'm not crazy afterall.

Curious, why did you buy an ECU for your car in the first place?

Ok guys, how hard is it to get an L1H1 for a good price? Look at this sensor:
https://cgi.ebay.com/ebaymotors/HONDA...spagenameZWD1V

It is advertised as an L1H1, but right below it says "L1H1 Equivalent". Perhaps I should just bite the bullet and buy a genuine L1H1 sensor. If I'm
going to do this CA to 49-state VX conversion, I won't want to be debugging
O2 sensor issues.

Gary

That's wierd, the Bosch 13246 is suppose to be the exact same sensor from NTK.

Read this: https://www.hondacivicforum.com/m_103656/tm.htm

Same problem we're having with the cheaper 79$ one.
I priced these out tonight and they're going for more than $400. How
come in 2001 or so these same sensors were going for less than $150!?
Gary

I got a new ECU because the mechanic said that was probably the cause of the fast idle. He said when he hooked up his fancy $7000 computer to my ECU, my engine RPMs weren't being read by his computer, and so that led him to think the ECU was faulty. My tachometer works just fine tho, so I dunno.

Umm... what are the right tools for removing the ECU then? I have 10mm socket, which I believe is needed to remove the bolts. But what about connectors?

Does this look about right for the tools I will need to remove my ECU?

https://www.technosquareinc.com/images/ECUREM/G3501.jpg Anything else I might need? Are the needle nosed pliers for removing the connectors?

The Helm's manual is $20 to purchase online. Someone on Ebay is selling it for $6 on CD. So I may buy that. But I have to wait for some money to get back in to my bank account first.

To remove the ECU...

Pull back the carpet (I think there is one plastic clip that holds that area of it down..though not 100% sure), and remove any clip that holds the carpet.

Remove the 10mm nuts that hold the ecu.

The plug just needs to be pushed at one spot, then pulled out. Do it by hand, not with the pliers since you might nick a wire or break the plug.

Install in the reverse order.
:thumbup:

Call it done.

Another development with my Check engine light. Soo... I started the car up this brisk morning, and the CEL came on about one minute later. I then did an engine off coast about eight or nine minutes later. Bump start, and CEL didn't come back on. But, then I stopped at the bank. When I came back to my car about five minutes later, I started it up and the CEL did NOT come back on. I drove to school with no CEL. I did one more EOC toward the end of my commute about 30 minutes later, something I have confirmed causes the CEL to turn off.

Another thing. In the Haynes manual, it says that the 48 code has to do with the heat sensor of the o2 sensor, or something like that. So maybe once the car is warm the CEL does not come on? But why, then, doesn't it turn off once the car is warmed up? It only turns off if I turn the car off and then start it again. If I don't turn the car off, the CEL will stay on. If I turn the car off and then 5 minutes later turn it on again via key start, or moments later (no more than say two minutes) then it doesn't come back on. I have a feeling this has nothing to do with whether I'm bump starting or not, but whether the engine has cooled sufficiently for the CEL to come on, which then makes me ask, why is the CEL only coming on when the engine is cool? If I turn the car off, eat dinner and come back 20-30 minutes later, then it comes on a couple minutes after I start the car. Anyway, I will attempt the ECU replacement today. Should I reset the ECU before I change it? Might this take care of the CEL?

What does anyone think about my CEL behavior?

Also, the commute this morning, the idle wasn't nearly as high as it has been the last couple days with the new o2 sensor. The first day it was pretty high - around 1300 maybe even 1400. Yesterday it seemed maybe slightly lower (probably because I bump started, which tends to keep the idle from going as high once that is done) Also, last two days it's been bouncing from 1000 to 1250 or so. Today it just kinda stayed at 1000-900 the whole trip. Maybe 1050, or max 1100 for very short period. Mostly only about 1000. So I thought that was kind of peculiar. Anyway, I'm still hoping my o2 sensor isn't bad and maybe a new ECU or resetting the ECU will fix the problem. I'll be sure to keep ya all updated. Thanks again to everyone for all the info and advice.

Hey J! Why buy, it's free online! It's a great manual - the bible for our cars.
If you want, I can try to find the link for you so you can download it.

About the CEL light. It looks like during the initial startup, ecu senses something not
right and sets a flag which is only reset when ignition is off. Once you turn it on again, ecu again checks o2 sensor but by then everything is ok (o2 warmed up).
So once on, o2 sensor light will not turn off unless ignition is off. Just a guess.

Perhaps ecu is checking the resistance of the heater circuit when cold. When cold the resistance is different than when the heater is HOT. The cold value of the heater is different than the OEM. When heater is hot, it checks out ok. Might want to check this out.
Gary

If something is wrong with the heater for the o2 sensor, it is the same thing as the o2 sensor being bad, since the heater is incorporated as part of the o2 sensor.

The CEL coming on in the cluster doesn't really matter though, and is only there to remind you to check the code stored in the ecu. The ecu should store the code until you reset the ecu (by pulling the fuse or the battery terminal).

It might seem promising that the light isnt on all the time and that the idle is one way or the other, but in reality, that is normal even if the problem still exists (which it still does when the cel is not on, it just isnt telling you then).

The reality is that something is probably wrong.

To be sure if something is wrong, first reset the ecu to maybe clear a code that was left from the last sensor. Do this by pulling the fuse under the hood for the ecu, or by pulling the negative battery terminal.

If the CEL comes back, then troubleshoot the problem.

No need. The ECU gets power to maintain it's diagnostic code memory through the hazard fuse. That's why pulling the fuse erases the memory. Unplugging the ECU from the car will have the same effect.

I doubt it.

Switching the ignition off shuts off the CEL, but the error code is stored in the ECU. Aside from the 2 second bulb check, the CEL only comes on when the ECU has diagnosed a problem. If you only get a code 48 from the ECU, every time the CEL comes on, it's because the ECU has re-diagnosed a problem with the LAF sensor.
The official road test conditions for a code 48 is to drive in 3rd gear with the engine speed at a constant 1500 RPM. Give it a try - 3rd gear at 1500 rpm, cycle the ignition off and back on when the CEL comes on... I bet it pops up again within a couple seconds.

That would be great!! I don't want to wait for the cd to ship and I don't want to pay $20 for it if I don't have to. :-/

Thanks! I will be leaving school soon and will try it then.

I don't think you need pliers :)... The socket and socket wrench is probably all you need.

BTW, I updated the heater comment. check it out... since you replied before I updated it. Looking for the link for the manual.

Gary

So are you suggesting that the o2 sensor may not be bad? My hunch is that it's not. I will look into it. thanks.

Jacinto ---
Here it is...
https://www.hondahookup.com/manuals/
You'll have to register, but it's worth it if you can get the manual for _FREE_!
Enjoy...
Gary

Hah, I just found one as well! Thanks tho! 88meg file, wow.
https://www.hondacivicforum.com/m_41699/tm.htm

The sensor is not what the ecu is looking for. Something is not right during your car's check of the wide band sensor.

Lets take a stab at this. If the ECU is testing the heater resistance and it's not to spec it will throw a CEL, that's a problem. But when the sensor is HOT and the ECU is ok with it, then perhaps it is not that big of an issue since the resistance now falls into the range that is expected.

Did the mechanic throw away the old o2 sensor? Do you have a multimeter at home or use one at school? If so, can you measure the resistance of the two heater wires of the new and old sensor when cold? I bet they are off (or not close).

Now for kicks, if you are willing to do this, heat the old one up with propane or just
reinstall in your car and run your car for 5 minutes at 2k rpm and measure the resistance of the O2 sensor again.. I know the mechanic cut the wire and if there is enough wire you can strip it prior to install to measuring the resistance. Do the same for the new sensor (measure the resistance when hot vs stripping the wires on it LOL). the results I would predict is that both O2 resistance will go down and the values will be closer together. In other words, the deltas between the cold values and hot values will be smaller when the O2 sensor is HOT.

Gary

You will never need us again LOL!
In fact, I predict you will be the VX guru sometime next year and thumb your nose at us! haha.

my mechanic is very anti-"internet people". He doesn't want to hear the advice or comments of what the guys on the gassavers forum think. First time I went to him I had copied and pasted all the different advice everyone on here had posted in reply to my questions etc and he takes the piece of paper and throws it up in the air. "Are they mechanics?" he says "If they're such great mechanics, why aren't they doing it for a living?" I tried to reason with him but given that I don't know anything about nothing, it was pretty useless. But I will try to get him to cooperate. He did throw away the connector end of the o2 sensor. I asked him if I could see him this afternoon. He said maybe he'd have time. I'm pretty confident we'll be able to dig up the other part of the o2 sensor. I actually do have a multi-meter at home, but I don't know how to use it. It has several settings. I'm not sure if the wires are long enough to reach from the o2 sensor to the ECU. I am NOT mechanically inclined and get overwhelmed by this stuff pretty easily. But I feel almost obligated at this point to make my best effort so as to not have all of you waisting your proverbial breath on me as it were. ;)

Haha, that'll be the day. With this manual, maybe I'll get to the point where I can actually put to use all the advice that has been given. Would be really cool if I did become somewhat knowledgeable tho. Wish me luck! I'll need all the luck I can get. :p

wow, this manual is 1258 pages. Unreal.

Because we get paid more than mechanics?!?

Don't talk about the internet in front of him. We're stepping on his toes through you. He has experience and good general knowledge about cars, but I doubt he has specific knowledge of the VX in general. In this case, VX fanatics will know more about the nuances and specifics of the car than most general mechanics.

Gary

Hey guys,
I found a place locally selling a Bosch 13246 for $199!
Supposedly, this is the same NTK sensor that Honda uses.
I have a coupon I can use so I might be getting this, although
this person had some issues with this sensor:

https://www.hondacivicforum.com/m_103656/tm.htm

Gary

Take a look at page 228 if you haven't found it already.

Good idea, but the LAF heater circuit is a code 41, not 48. :)

I just happened to be searching on L1H1 sensor and I happen to click back onto this thread and noticed post #2 of this long thread.

Check out what Jadiasman said about his error (code 41). Jacinto's error code is 48. Not consistent...

From jadiasman:
The sensor that ebay store is selling looks just like the one I bought from autozone.com in 2005. If you notice the sensor has a blue wire which to my knowledge only came on the L2H2 sensor. For my 92 VX at least, the L2H2 sensor did not function properly (code 41 - sensor heater).

editing: noticed jadiasman bought his from autozone (Jacinto's from Ebay).. ignore this post.

Ok guys, after doing hours of research on this, I can tell you one thing. If you want to get a real L1H1 sensor you can only go to Honda for that. The reason why the L1H1s are so expensive is because only Honda can sell em. They are made by NTK for Honda. At one point in time, there was grey market L1H1. Honda or Horriba had an issues with that and took it up with NTK so the grey market supply of L1H1 were cut off. At the time you can get real L1H1 sensors for $99 or so. They have all gone up since then and are about $400 now. If you noticed on ebay, all the civic vx sensors are listed as 5-wire or l1h1 equivalent. Also, they list these sensors as working with VX and the insight, but the two sensors have different part #'s from Honda. Go figger. So.. I'm not sure what I'm gonna do right now.... Take the plunge and shell out about $400 (best price for a real one from SL Honda is about $370). I'd say this Ca to 49-State VX conversion will only save me about $120/year in gas so it'll take about 4 years to recoup the cost. I already bought the ECU so I think I'll just sit tight until someone gives me their used L1H1 sensor or sell me one for cheap....

Gary

Ps. to read more about this: https://www.honda-tech.com/zerothread?id=481895

Wow. THat is a very informative article that is in that previous post!

Sad for us VX owners looking for a cheap sensor though...

This is true, and I agree totally, but he did raise a valid point, which I feel bad bringing to light in front of this forum. No one has actually helped me solve a problem with my car on this forum. I haven't adjusted the screw on my throttle body yet, so maybe that will help, but with other things all the solutions have ended up coming from the mechanics. The sticking idle no one could figure out. The mechanic figured it out. BOTH mechanics came to the conclusion that the culprit was probably the throttle body. No one on this forum thought it was that. Another problem someone tried to help me with was the headlight. I drove home with the headlight not fixed. First thing the mechanic asked me was "did you check the fuse?" I was like, "I dunno" anyway--it was the fuse. Third thing was the VSS. Everyone on here said just replace the VSS sensor. I did do that. My speedo and odometer are still not working. Both mechanics said the cluster needed to be replaced. Even the guy who sold me the car said replace the VSS. Someone on craigslist selling their car that had the same problem as mine "the speedo not working all the time" also said "but it's an easy fix, just get a new VSS" yet, when the correct solution to the problem is a new cluster. A VSS will not fix a speedo that doesn't work some of the time (versus all of the time)

I agree, tho, in regards to VX specifics, you guys definitely know a lot more than both of the two mechanics who have worked on my car combined. I have to continually stress to them that it's a VX. The first mechanic didn't even know what a VX was. I had to repeatedly explain to him that it was a special model. Not a "DX". But... the mechanics have tons of experience from working on soooo many cars! Think about how many cars they have fixed! They fix about 5 cars a day or more. Most people on here have worked on their own cars, so they are going on their experiences of their individual car. But that isn't always going to transfer to everyone with a VX or a Metro or a Saturn. I guess my point is, we shouldn't be belittling the mechanics. Yes, they charge a lot, because they can. I understand they do make mistakes as well, but so far the mechanic I've been seeing has been doing pretty well by me. They do know their stuff by and large. They have an enormous amount of experience.

That said, please don't get me wrong, I value this resource. The spirit and willingness to help each other is really really great. I feel like I'm a part of a little niche community. Obviously many of you have a great deal of knowledge with cars, and there's been a great deal I've learned about my car through this site, which mechanics could have never told me. Besides, there are ways in which mechanics are kinda dumb. For example, it took my mechanic an hour or more to tell me the code was the o2 sensor with all his fancy computers hooked up. Why couldn't he have just used a safety pin? It's not like he was able to give me specific information in the end of the day. "It's the o2 sensor." That's all he could say. Couldn't tell me anything at all the nature of the problem with the o2 sensor. I don't know what he was doing the whole time, but it was a little bit embarrassing. How long did it take me with the help from the people on this forum? 2 minutes? So I don't think I will fire my mechanic just yet TomO, but through the friendly help of everyone here, I will try to use him less and learn to be a little more self sufficient when it comes to fixing my car!

I did it Bobski. I drove for a little less than 2 miles at 1500 rpm in third gear. The CEL never came on. From what I've noticed, it only comes on when the engine is cool. If the engine is hot, it won't come on. But the engine only needs to cool a little for it to come on. I'd say somewhere between 5 and 10 minutes of the engine being off it will come on the next time I start the engine. Less than 5 minutes after the engine is hot, I would say that it will not come on again. I have ruled out that it has nothing to do with bump starting, because I turned the engine off coming back from school before the engine was hot, and when I bump started the CEL came on. There is a direct correlation between hot engine and no CEL.

Gary: No dice on getting my old o2 sensor back. I couldn't find it in the dumpster. Mechanic had no intention of taking any responsibility for cutting it for me. I even explained to him that I had taken it to him to do so I wouldn't have to cut the wires. Oh well. I'm stuck with this o2 sensor. My gas mileage doesn't seem to have taken a drastic hit tho. It first hit half tank at 250 miles. That's about typical. I've been driving less efficiently this tank. But we'll see by the end of this tank.

One more thing, he said I wouldn't be able to solder the wires together. Because you use led to solder and led would interfere with the very sensitive o2 sensor's wires sensing of resistance, which is what he said the wires do.