eiloo

I found the following codes from an OBDII on a 01 Civic EX.

It started a few weeks ago where I was driving on a freeway, exited and then it slowed drastically, almost coming to a halt. I kept the gas pressed and it moved VERY slowly and I was able to get into a residential area to stop. I opened the hood and my wife said she could smell something burning. I didn't smell anything at all.

I've taken out fuse 6 to reset the MIL but it came back with 5 codes:

2 - P0420 - Catalyst Efficiency Below Threshold (Bank 1)
2 - PO133 - HO2S-11 (Bank 1 Sensor 1) Circuit Slow Response
1 - P1298 - Electrical Load Detector Circuit High Input

I didn't see a thread that specifically mentioned these three in combination.

Any help would be much appreciated! I would consider myself pretty handy (though still a newbie with cars) so if I can repair this myself, that would be best.

If it makes a difference:

MIL DTC
P0420

Pending Codes
P0420

Stored Codes
P1298
P0133
P0133

What do the different levels of codes mean in this case? Any thoughts on why two of them are duplicated as well?

It Wasn't Me

Troubleshooting P1298

1. Reset the ECU. Remove fuse #6 (15 amp) from the fuse box under the hood. Wait 30 seconds then reinstall it.

2. Start the engine.

3. Turn on the headlights.

Does P1298 come back up?

Yes - Go to step 4

No - You're okay, but check for poor connections or loose terminals at the ELD and ECU.

4. Turn the headlights and engine OFF.

5. Disconnect the ELD 3-pin connector.

6. Turn the ignition switch ON (II)

7. Measure the voltage between terminal #1 (black/orange wire) of the ELD connector and a body ground.


Wire side of female terminals

Is there battery voltage?

Yes - Go to step 8

No - Check the #4 (10A) fuse under the dash. If the fuse is okay, you have an open wire between the ELD and that fuse. Find it and repair it.

8. Turn the ignition OFF.

9. With a jumper wire, connect the #3 terminal (green/red wire) of the ELD 3-pin connector to a body ground.

10. Disconnect ECU connector E (31-pin)

11. Check for continuity between terminal E15 (green/red wire) and a body ground.


Wire side of female terminals

Is there continuity?

Yes - Go to step 12

No - There's an open in the wire between E15 and the ELD. Find it and repair it.

12. Check for continuity between terminal #2 (black wire) of the ELD 3-pin connector and a body ground.

Is there continuity?

Yes - Go to step 13

No - There is an open in the wire between the ELD and (ground location) G201. Find it and repair it.

13. Reconnect the ELD 3-pin connector and ECU connector E.

14. Start the engine and let it idle.

15. While measuring the voltage between ECM/PCM connector terminals A24 and E15, turn the headlights on high.


Wire side of female terminals

Does the voltage drop?

Yes - Replace the ECU with a known-good one and re-test. If it tests okay, the ECU was the problem. Just keep the new one.

No - Replace the ELD

It Wasn't Me

It's under the hood, on the a-pipe (aka downpipe) just beneath the flange where the manifold connects to the a-pipe. Yeah, it's got four wires coming out of it. One black, one gray, two white. Impossible to miss.

Definitely an easy fix. You may or may not want to invest in a specialty socket for removing o2 sensors, but it isn't required.


Naw, but here's a helpful thread on the subject. Link There are more threads, but you'd have to Search for them.


Not off the top of my head, but just shop around for the best price. There is a list of online OEM parts suppliers, as well as a link to our Sponsor Marketplace in the FAQ's.

lazlong

O2 sensor is #18: http://www.bkhondaparts.com/billkay/...itch=&hidIrno= $60 is pretty f n reasonable even compared to other model civics.

ELD: http://www.bkhondaparts.com/billkay/...ton&catcgry1=#

btw: The list price is about what you would pay at the local dealer.

eiloo

Thanks Everyone.

So here's the situation. I was looking under the fuse box to purchase the ELD. The seller had two sizes and I needed to know which one I should order. So in the process of getting the fuse box up and figuring out that I needed to remove the 40 and 80 fuses, I decided to start the car to make sure it still worked. It started fine and the CEL was off. So I grabbed the OBD and scanned for codes and the only code that remained was the P1298.

Any thoughts on why the P0420 and the P1033 disappeared when I didn't repair those yet? When I get the ELD next week, I'll install it and scan with the OBD to see what's left.

Does it sound odd that just trying to get the ELD out had caused everything but that code to disappear? I didn't pull the positive off the fuse box. Everything was intact aside from my pulling the 40 and 80 fuses.

It Wasn't Me

Fuse #19 (the 80 amp fuse) is the Battery / Power Distribution fuse. You reset the ECU when you removed it. Test-driving the car will tell whether or not the problem with the sensor/cat codes were intermittent.
Reset the ECU.
Start the car and hold it at 3,000 RPM until the radiator fan comes on.
Jump on the freeway and drive until the CEL comes on. If it doesn't come on, return and scan the car anyway.
Is temporary DTC P0133 indicated?
If it is, replace the o2 sensor. If it isn't, the problem was intermittent.

Did you troubleshoot the ELD code, or are you just going to replace it and hope that fixes it?

eiloo

The P0133 came back on last night. Two of them, one is in Freeze Frame and one is Temporary. So as soon as both parts come in, I will install them and see how it goes.

I guess you could say I took the "easier" way out with the replacement of the ELD (even though it may not fix the issue). Honestly, I wasn't sure as to how to begin testing with measuring voltage and searching for the open wires. If the fix doesn't work, I guess I would be out the $20 for the ELD and will be back here for to review your troubleshooting steps.

So I guess I'll need a multimeter to read the voltage. Any chance I'll hurt myself or the car by pressing on the wrong parts? Guess I'm just unsure of where these different terminals are and how to test them for voltage.

kmcormick9

My car was having similar symptoms and had the same DTCs and it turned out to be a failed cat.

eiloo

So I had replaced the ELD and no codes came up after I have taken a few trips around town. No freeway speeds though. I checked the OBDII again after my last trip last night and still no codes. Previous to last night, the O, C and EV icons were flashing on the OBDII but they've become solid so I'm assuming those tests have run and come back fine.

I guess this may depend on the way the inspectors test vehicles but is there a good chance that the car would pass emissions? The light is currently green on the OBDII.

I've been reading that the O2 sensor should be changed at around 100K. Since I have it, I will swap it out.

Does a bad O2 sensor cause the cat to perform poorly as well?

As previous posters have mentioned that it may be a failing cat, I've prepared myself for that cost. Is that an easy fix for a non-mechanic or should it be taken in?

Thanks again for everyone's help!!

honda.lioness

A bad O2 sensor can cause emissions to be off and so overheat the cat, resulting in damage to the cat.

I think it is a good idea to change the O2 sensor at 100k miles. You can get an OEM identical one for under $50 through Amazon. Get only NTK or Denso. Google for {NTK oxygen sensor} to get to sites that let you put in your make and model and then tell you which NTK sensor to get. Same for Denso.

Buy a proper O2 sensor wrench from Autozone, Pep Boys, or Harbor Freight for around $10. Then it is pretty easy to remove the old sensor. I like the O2 sensor socket wrench that lets me use a torque wrench. To remove the old sensor, maybe soak the threads with PB Blaster and then drive for a few days. This seems to help the PB Blaster penetrate and do its work. The old sensor should come out easier if the engine is still a little warm. Do not burn your hands working near that exhaust manifold. :-)

eiloo

Thanks for the tips on the cat.

I replaced it yesterday. I had come home from a trip and probably left the car for a couple hours before attempting this project. During the time it took to get the old one off, I thought it was going to be a breeze getting the new one on. So much for that. I think it took me longer to put it on because I needed to let the wire dangle and it would get caught here and there. All in all, a relatively easy fix. Being in the position it was, I'm not sure if the socket would have worked well. I ended up using a pair of pliers since none of my wrenches or sockets worked. The engine was slightly warm to the touch, not hot enough for a burn.

Now the test is to see if we get codes back. I haven't driven far enough for the O, C, E and EV codes to remain solid on the OBD so I'll see what happens after that trip.

Thanks everyone for your help and tips along the way!

It Wasn't Me

Good luck with it!

eiloo

I'm back... So after a number of trips the CEL came back on tonight.

Permanent P0420
Pending P0430

Am I correct to to assume that I should have replaced both the upstream as well as the downstream O2 sensor since I'm over 117K on the car?

Is the downstream sensor also 4 wire?

It looks like P0430 is for the downstream sensor right?

When I end up getting a new catalytic converter for the car, would the techs recommend changing the O2 sensors anyways?

How hard is the fix for the average person for replacement of a cat?

Is getting underneath the car with a creeper enough room to get it done or should it be lifted in the air for a proper fix?

Thanks!

honda.lioness

Chatter like that at https://honda-tech.com/forums/honda-accord-1990-2002-2/p0420-catalyst-system-efficiency-below-threshold-bank1-o2-cat-1154743/ point to replacing the cat converter. I would do this next. I would not replace the downstream O2 sensor at this time.

Online OEM parts sites want about $500-$800 total for the OEM converter. 01-05 Civics will have a converter integral to the exhaust manifold or in the downstream piping under the car, depending on which submodel (LX, DX, EX etc.) one has. You should consider aftermarket converters, too, though aftermarket may not last as long. It does not look too hard to remove. Have PB Blaster handy, soak bolts overnight, drive a bit, etc. I would welcome your report on removing it.

You should be able to sell the old OEM converter to a junkyard for a nice rebate of $25 or so. Maybe more. It has precious metals in it.

Cat converters are supposed to last the life of a car. My bet is that your upstream O2 sensor was a bit off, or plugs were not changed often enough, or similar, so your cat died early. Of course a wire could just be loose, too.

See densoproducts.com for descriptions of your Civic's oxygen sensors.

eiloo

Well after doing some research online, it doesn't sound TOO difficult to replace the cat. My question now in shopping around is that is it the whole pipe length shown on bkhondaparts that I need or is it the actual cat that I need Part #4. http://www.bkhondaparts.com/billkay/...itch=&hidIrno=

I'm assuming I can reuse the existing heat shield if the new one doesn't come with one.

I'll head under the car to check this out in some more detail and see how it is.

It Wasn't Me

Yes, part #4 is the one you want. It's a bit less expensive at Majestic. Click Here.

Pretty sure it comes with the heat shield, but I'm not 100% on that. If it doesn't, you're better off just leaving it off. They're a serious PITA to remove once the nuts seize up.

As far as replacing it, be prepared to replace some nuts and bolts. You might even need to cut the old ones off, if they're rusted enough. (I've seen it, many times.)

Basic tools is all you should need in order to replace it. It's always easier with the car in the air, but some jack stands should suffice. As long as you can get under the font-half of the car you should be fine.

eiloo

Any suggestions of a brand of aftermarket cat that's been reliable/decent reputation if I decide against OEM?

Lots of brands out there to choose and getting all confused now.

It Wasn't Me

Megan seems to pop up a lot. Most likely due to how inexpensive it is. There are better choices, but I haven't seen anyone complain about the Megan. (yet)

eiloo

I took a look on the Megan Racing site but saw the test pipe which doesn't have a cat on it. Honestly, I'm not really into the racing jargon so I'm lost on their site. It may be on their site, but I'll have to continue to dig.

Is there just something they offer that is a replacement for a stock cat or another manufacturer you would recommend? Magnaflow? Bosal? Walker?

Edit: So I wasn't going out of my mind on the Megan Racing site. They don't have cats. http://www.meganracing.com/contact/answer.asp?faq_id=11

honda.lioness

Magnaflow for aftermarket catalytic converters

eiloo

Thanks!

So on the Magnaflow site, what's the difference between the two direct fit parts listed?

http://www.magnaflow.com/02catalytic...IVIC&year=2001

93228 and 49483?

honda.lioness

From bkhondaparts.com, I see the 2001 LX and DX have a catalytic converter integral with the exhaust manifold. The EX and GX have their cats further downstream, in the exhaust piping, and are $200 more expensive, so. Hm.

I did not realize your cat was in the exhaust piping. In 2008 my 91 Civic failed emissions. I put a direct fit magnaflow cat on it. The magnaflow cat fit pretty well, and it was not hard to replace, as long as you have PB Blaster. Being picky, at one point I went to the hardware store for a couple of better fitting bolts. The 91 Civic passed emissions with room to spare. Several months later in another state, to my dismay it failed emissions. I never found the cause. I am inclined to think the OEM cat is worth the money.

(Double check: Are you in California? If so the cats you found at the magnaflow site are wrong.)

Google a bit for the best price on the magnaflow. Lots of distributors sell them.

(You're welcome.)

eiloo

Thanks for the insight. I'm in PA so no worries on it needing to be CARB. In PA they do an OBD and Gas cap test from what I can tell on cars 1996 and after.