Malfunction Indicator Lamp

This light came on today and will not go off. The manual says it is a emission control system problem, but first check the gas cap. Wait til after 3 driving trips if that was the problem.It was not.
1. Is it ok to drive for a few days or is it serious?
2. What kinds of problems can it be?
I hate to bring it somewhere and get hit up for a major problem and it was something minor..
Thanks for any help in advance..
hondagirl23

Well, unfortunately, can't really help you unless you pull the codes from the computer. I can suggest you try to tighten your gas cap... 3 clicks usually does it.What year is your car? If it has an obdII system, just head over to autozone and have them check it out.
But yeah, it shouldn't damage the car to drive it around. But remember, if the light doesn't go out, go get it checked. Something as simple as a oxygen sensor or a clogged egr valve isn't worth a new catalytic converter.

deaz, thanks for the quick reply. As i stated above, I already checked the gas cap and drove a half dozen times andlight stays on.
I once had a bad gas cap on another honda.Dept. of Environmental Protection were giving free test and it leaked but i guess i did not have a warning light for this on that car.
This Accord is a 98EX. Are you saying that Auto Zone can check it out with one of their freebie test?

Yes, just go to autozone, and ask them to check your codes. Just remember to bring a piece of paper and a pen with you. Then, when they are all done, they'll tell you the code numbers, and if they don't tell you what they mean, just ask, and the guy will pull out a book of codes for your car, and will tell you what each of them mean. You may get one, you may get 3. Usually if one sensor goes bad, it affects a few of them. (In my experience anyway). So, just get the codes, and then bring them back here and post them and let the experts decide. But remember, a driving cycle is not just a "turn the car on, go round the block, turn the car off", it actually is more than that. I think its a required 10-20 mile drive? Not sure, havn't had to do one in a while, so really don't remember.

Also, with that year car(same as mine), if you go into the passenger fuse box, and pull out the clock fuse, and then put it back in, it will reset the ecu, and clear all the codes. Then just turn your car back on, let it idle for about 15-20 mins without driving it, and without having any accessories on, and then keep driving it around, if the light comes back on, then you definately have a problem, otherwise, it was just a fluke. But it wouldn't hurt to get the codes pulled from autozone first though, just to know what the problem MAY have been.

This was very helpful!! I just printed it and will follow your instructions.
Seems like i used to have a sensor go out on my 90 accord about once a year and it was kind of a pricy part. If i remember correctly it was over $100.00 for each repair. Guess it could be worse. I really love the 98 Accord. I was just thinking 2 days ago about how I have not had any mechanical problems with it since I bought it 2 years ago. The Ac has not been to cool lately and I brought it to the dealer 2 weeks ago.(it was under a year warranty from last year visit). They said everything was fine but it was a icebox when I got it back from them. I just had freon added last year and checked for leaks.I am wondering if there is a small leak and they just added more freon rather then fix a leak? Honda service is usually super in my area.
Getting back to my problem. I did two 20 mile drives yesterday and will do another tomorrow heading to Autozone but i want to try the clock fuse suggestion. Do I understand correctly, Go to Autozone first before I do the test???

Yes, go to autozone first, otherwise when you go there, there won't be any codes left in the computer to pull. But yeah, honda ac's aren't exactly the coldest.. Not sure why.. I went and drained/recharged my system, and the air has been much much colder, but still, even on hot and humid days, it still doesn't work all that well.

Autozone clears the codes after they have pulled them, so there wont be a need to pull that fuse to reset the ECU.

Autozone did a test with a hand held device and the following is the info they gave me after the test>>>

TROUBLECODE OBDII (ALPHA) P CODE

TROUBLESHOOTING PO420
The PCM has determined that the cataylst system effeicency for Bank 1 is below threshold for the correct engine operating conditions.(Bank 1 identifies the location of cylinder #1, while Bank 2 identifies the cylinders on the oposite Bank) <<<This is all i received. Does this help?

I see message from moderator below that Autozone clears the codes after they have pulled them, so there wont be a need to pull that fuse to reset the ECU.Does that happen automatically? I ask because the MALFUNCTION INDICATOR LIGHT is still on.

Well once you fix that problem, go back to autozone, and just ask them to clear the codes. They use the same handheld OBDII scanner and it takes 10 seconds.

What this code means (bare with me as I'm not 100%positive about you're specific stock exhaust setup) but typical exhausts have 1 or 2 catylitic convertors and a few oxygen (o2) sensors. The o2 sensors relay air/fuel readings back to the car's computer. This error is telling you that the computer is noticing a discrepancy from what it wants to see. Some possible explainations are:

1) An exhaust leak...this can be cheap or relatively expensive to fix, depending on if the leak is from an $8 gasket or a few hundred dollar exhaust pipe. A leak would cause an exhaust like smell, an increase in engine noise (how much of an increase depends on the size of hte leak) and also if you look under hte car, you may actually be able to visibly see exhaust gases escaping from a random point somewhere amount your exhaust pipes under the car. This exhaust air escaping would cause discrepancies between the o2 sensors readings...and the computer would be confused. This isn't that much of a big deal, except that it affects performance, and if left unchecked the leak grows and can rot out an exhaust pipe entirely.

2) A bad o2 sensor...one may have just gone bad, causing discrepancies in the readings...computer throws a code. This would need to be replaced as soon as possible

3) One (don't know if you have multiple) of your catylitic convertors has gone bad. Typically this results in poorer gas mileage and performance. Possibly excess carbon (soot) on the exhaust tips, smell of unburnt gas from exhaust, smell of rotten eggs, etc. Unburnt gases aren't being neutralized by the cat converter and are escaping past to the next o2 sensor...it notices excess gasoline vapors in the exhaust, and warns the computer.

Pretty much all 3 of these will cause poorer performance, gas mileage, etc, and will/may cause you to fail emissions inspection. However, none are hte end of hte world. Your car wont blow up...you can drive on it, although not recommended...it is safe to drive if you don't have the money to fix. The first two shouldn't be TOO expensive to fix, the 3rd can be ridiculous. Many dealerships want $1,000+ for a stock replacement cat. Many people simply go with an aftermarket cat becuase they are cheaper. Only don't do this if you live in California...as they wont pass their strickter emissions there. Anyway, my advice would be to take it to a local exhaust shop...not a dealership (unless it is still under warranty). And have them check it out and fix it. Dealerships will only use stock replacement (expensive parts) and will charge ridiculously high labor costs. Local chains like meineke are generally a bit cheaper, and privately owned mom and pop garages are usually cheaper (usually!) Well I'm going on and on, but yeah, get it checked out and report back what they say, and we will do the best we can to help you there.

I would try to avoid paying to get it repaired until you have it checked out and then check back with us. Some mechanics are pricks and try and take you for a ride. So unless you have one you trust, check back here and we'll try to help.

Ok, Here is what happened. Last night I got a fill-up and drove on home. Car has been running fine during this whole thing with the Malfunction Indicator Lamp. Today I was driving to town and the light turned off....Could it of been something simple, like the new fuel corrected the problem or something that might of stopped malfunctioning? I called Autozone to see if they reset the codes. The store I went to, said they have not been allowed to reset them for awhile, since a employee caused a problem to someone's car after resetting the code a long time ago.That is what i was told. Anyway, should I just wait n see or is there still a problem even though light went out?

hi, i've got a 98 accord ex 4cyl and i have the same problem. only i know how to fix it but i do not have the cash. the catalyst code for me was <according to honda> after i put bosh +4's in my car. it has run great since i did it, but hte check engine light has been on for almost 2 years and i still get 400 niles to the tank. anyway i found the problem the o2 sensors have had a hard life after 120k miles and they really need replaced. while i'm at it i'm going to change the cat. autozone has one that is a direct replacement for what i have and its about 100 bucks.

o2 sensors have a lifespan, usually between 80-100k miles and then they wear out. cat's have to last 85k miles according to the EPA. if it goes before then its a dealer warranty item. good luck

Damn dude, you get 400 miles/tank? What kind of fuel do you use? THe most I ever get out of my tank is around 350, and thats when I fill it up when the fuel light stays on... (I estimated it to be about 24.5mpg)

Are you talking about the Malfunction Indicator Lamp or another warning light? You mention Check engine Light. I just want to be sure. And if mine went off and has stayed off...then could the problem of been temporary or means something is gonna go bad sooner or later. What are Bosch +4's? Plugs?
I am due for a tune-up if that could cause the problem. I am averaging 29-30 mpg with regular driving. Very happy about that! I am at 103,000 miles. I guess it is time for timing belt and I have neglected to get my 90,000 mile service.Guess I should get those things done. It will sting my bank account though.

Well, heres my suggestion. If you are due for a tuneup, do the following first:
Distributer cap, spark plug wires, some ngk spark plugs, or even bosch's. (I use bosch+2's, give me some nice spark) Check your vacuum hoses, replace all your fluids if you havn't been, and I'm not sure whether or not you have a manual or an automatic, but it wouldn't hurt to get all that stuff flushed out either.

Then: Start saving up to have your timing belt and all that replaced. If you don't mind doing it yourself, it will save you a bit of cash. Just checked on the autozone website, and timing belts only cost between 15.99-31.99. So, as long as you don't mind doing it yourself, it wouldn't hurt. Also, if you don't already have a haynes manual, I would suggest getting one. They are invaluable to the backyard mechanic. Otherwise, for a timing belt installation, you're probably going to be running anywhere from $200-$400 probably. Just be careful, and follow all the directions in the manual, otherwise you could mess something up.

But about your malfunction indicator lamp, it is the same thing as a check engine light, just two different names. Now, heres my question... You aren't confusing anything with the maintence required light, are you? Anyway, as far as the check engine light going off, it could have been something as simple as some really bad gas. I have a set gas station I always go to. And I use namebrand gas, not that cheap stuff. (When I mean that, I mean gas that I know where it has come from, not some stuff thats been sitting in a tank for years, and they are trying to get rid of it)

BTW, did you happen to get my e-mail?

Damn dude, you get 400 miles/tank? What kind of fuel do you use? THe most I ever get out of my tank is around 350, and thats when I fill it up when the fuel light stays on... (I estimated it to be about 24.5mpg)

i use whatever is the cheapest, i do about 70% highway driving and 30%intown. i run mobil1 5w-30, and change my filters, pcv valves, and air filters on a regular basis. tire pressure is also important.

Deaz
I found your email in my junk mail..sorry bout that. Thanks for replying.
I'm not very mechanically inclined.just plugs, oil, filter and such. I would rather the pros take care of the tough stuff. don't have a clue about a timing belt and not ready to learn..lol My accord is a automatic Ex model. Timing Belt, with water pump and other belt is much more then $200-400 around here.Seems like it was closer to 1,000.00 with a few other things.Hopefully that was including the 90,000 mile ck up.
No not confusing the light with maintenance light. Already dealt with that before lol I did go t oa different gas station before this happened. I usually go to Walmart.Never had a problem with them and there gas is constantly new. Might of got some bad gas due to all our Hurricane problems in pensacola.. We kept running out of gas down here.It sux..hondagirl


Well, heres my suggestion. If you are due for a tuneup, do the following first:
Distributer cap, spark plug wires, some ngk spark plugs, or even bosch's. (I use bosch+2's, give me some nice spark) Check your vacuum hoses, replace all your fluids if you havn't been, and I'm not sure whether or not you have a manual or an automatic, but it wouldn't hurt to get all that stuff flushed out either.

Then: Start saving up to have your timing belt and all that replaced. If you don't mind doing it yourself, it will save you a bit of cash. Just checked on the autozone website, and timing belts only cost between 15.99-31.99. So, as long as you don't mind doing it yourself, it wouldn't hurt. Also, if you don't already have a haynes manual, I would suggest getting one. They are invaluable to the backyard mechanic. Otherwise, for a timing belt installation, you're probably going to be running anywhere from $200-$400 probably. Just be careful, and follow all the directions in the manual, otherwise you could mess something up.

But about your malfunction indicator lamp, it is the same thing as a check engine light, just two different names. Now, heres my question... You aren't confusing anything with the maintence required light, are you? Anyway, as far as the check engine light going off, it could have been something as simple as some really bad gas. I have a set gas station I always go to. And I use namebrand gas, not that cheap stuff. (When I mean that, I mean gas that I know where it has come from, not some stuff thats been sitting in a tank for years, and they are trying to get rid of it)

BTW, did you happen to get my e-mail?

Yeah, we used to have the same problem when I used to live in Ocean City, NJ. Well, not the same, but still... The salt water would end up eroding the tanks and every 5 years or so, the tanks would need replacing. Unfortunately, they still would leak, and salt water would end up getting inside the tanks, and when they started running out of fuel at the pumps, thats when the problems would usually start. But yeah, I was incorrect about the pricing. I still need to do mine (102k miles), but I'll probably do that myself. As far as I'm concerned, never hurts to learn, and the worst that'll happen is that the car is off the road for 2 days, instead of 1, lol. The only suggestion I can give you really is to find an ex-honda mechanic, that works out of his own shop. They'll give you a MUCH better deal. If you lived here in Jersey, I could give you the name of a guy who does honda-only work, and used to be a dealer mechanic. Anyway, hopefully you're lamp will stay off, if it doesn't well then, post back here and we'll keep trying to help you out =}