Down the Check Engine Light Rabbit Hole

I have a 1999 Honda CR-V that has never given me any trouble. Until a couple of weeks ago, that is. It wouldn’t start when I tried to leave for work. It was turning over, but just not starting. So I had it towed to a local shop I’d heard good things about. They said it just needed a tune up really badly, which seemed odd but kind of a relief so I said go for it. After the tune up they took it for a drive and the check engine light came one. So they ran the codes and said it needed a new oxygen sensor. OK, fine, got it home and it ran like a dream all weekend. Then, on the way to work Monday morning, it died on the freeway. Another tow, this time to a shop near work as the first one was too far away. They diagnosed it and said the distributor had failed internally. Replaced the distributor, charged me $900 and sent me on my way. Now I’m into it for $1400 but feeling OK. Except that the check engine light came on as I drove it home. Back to a third shop (this one is part of the same local chain that replaced the distributor). They ran the diagnostics and said the catalytic converter had gone bad, probably because so much fuel was being dumped into it. They want a grand to replace it with a Honda part because they say the sytem is too sensitive to get an after market cat. They also said the first two problems, the oxygen sensor and the distributor failure, were unrelated. Seems a little coincidental to me. Also that there’s no real rush to replace the cat as it’s not going to cause any other problems. (Which leads me to wonder why the heck they think I need the Honda part if it doesn’t really impact anything else…)

My question is twofold. First, are these problems really unrelated or did the mechanics at the first or second shop miss something they shouldn’t have? Second, is it really necessary to get a genunie Honda catalytic converter? And, OK, cheating here by asking a third, this car has 160,000 miles on it. I know that means it’s going to need repairs once in a while, but I need it to be reliable. Is this all a sign that I need to bite the bullet and buy a new car?

“they ran the codes and said it needed a new oxygen sensor.”

They may or may not have been right.  There is no code that says replace the oxygen sensor. There is a code that says that there is a "possible" O² problem, but not one that specifies the sensor.  

" this one is part of the same local chain "  I would try and avoid all chains.  Usually the best bet is a local INDEPENDENT shop.  Chains generally are only interested in  immediate profit and minimal effort on their part.  I can't say anything about your local shops, they may be fine, but the economics of the situation is usually against the customer. 

 "They said it just needed a tune up really badly, which seemed odd"   Why do you say that?  Was there a recent work done?   Have you kept the maintenance up to date or are you behind?

It sounds to me like its possible that you neglected this thing to death - maybe even just for want of a change of spark plugs.

“Tune up”; doesn’t mean anything specific. Specify exactly what the first shop did.

And as JE Meehan noted, those error codes don’t say as much as people think. Find out exactly what error codes have come out of the computer each time the check engine light has been on and post them. The codes look like “P1234”

Hondas that strand their owners almost ALWAYS…have a failed ignitor in the distributor or a failed main relay. We used to keep 3 good distributors and relays on hand for Accords, Civic, and the other popular HOnda engines…there aren’t that many actually. Almost every Honda shutdown had something to do with the ignitor, the main relay…or the distributor in some way…OBVIOUSLY…weeding out other readily apparent issues FIRST.

SO…they replaced the distributor…and it didn’t fix it eh? That means they are missing some OBVIOUS issue…what issue? Coil overheat perhaps? Main relay issues? I used to have to kick my dangling main relay in my prelude to get it to start sometimes…lol…I was lazy and didn’t clean it up…I did eventually, but during my laziness…I’d just kick it…worked like a charm…that kicking would jar the eroded contacts and force them to make contact…

What people don’t get…or what shops prey on people with…is that your car will throw all kinds of codes…to try and tell you whats up…however one failure may trigger 3-4 codes…they SNOWBALL… and all point back to the original part failure…so one failed part may trigger many codes all at once…the trick is to be levelheaded and sort thru the failure codes…and track back to the real issue…NOT to THROW parts at every code you get…those codes beget each other…A failed this may trigger that…and also this and this along with it… SaVvy? They shouldn’t react to each code with a PART damnit…I hate to hear stories of shops doing this to people.

I FIRMLY believe someone missed something obvious in the early stages…could have been weak spark plugs…and or leaking wires. I’m STRONGLY leaning twd a main relay issue now… Then they put a new distributor in without finding the root cause.

SO…did they do a tune up? Plugs, wires, cap rotor, fuel filter etc? NO harm done in getting a tune up…HOndas run so reliably they actually cheat themselves out of regular tune-up’s…everyone fall into this pattern with a “reliable car”… Did they check for valve cover leaking into the spark plug holes and grounding out the spark?

This can be SO many things and I am so sorry you are going thru this… It is something I believe related to the ignition…like a main relay…coil, cap rotor, wires…somewhere in there.

They need to step back and take it slow and stop suggesting parts for codes…the codes aren’t to be used in this fashion. I’m leaning twd your main relay…when you had a failed start the relay didn’t make connection for the fuel pump and or ecu… Then when it failed on the highway…it probably LOST that connection bec the contacts in the relay are ERODED…you can clean them up actually… These guys at shops don’t know or DO KNOW what they are doing…to get their boat payments in order that is. THEY MISSED SOMETHING OBVIOUS…I GUARANTEE IT.

Wish you were local to me…I’d fix you up in a Jiffy… Grab a main relay and try it…New or even one from a yard OR your current one…crack it open and clean up the contacts inside…even… see what you get…SORRY for writing you a book here, but…I guess I was thinking out loud…I tend to do this…the guys here merely “tolerate” me I think…


First thing you need to do is get the actual code, not someone’s interpretation of it. Unless you live in California, you can got to most autoparts stores and they will read it for free. If you can’t get it read for free, and the mechanics at the places you have been going to won’t tell you what the code is, then you should buy a code reader for yourself.

You can get a basic code reader for about $60 at most autoparts store and for less than $40 at Harbor Freight. At the auto parts store, they will show you how to hook it up if you buy one there. If they won’t, just go to another store, but be clear first that the sale is contingent on getting instructions. Once they show you where the connector is located, you just plug it in and when it says ready, push the button. It will come with a book telling you how to clear the codes etc.

Post the code here and you will get plenty of help.

This sounds like a neglected car to me also. However, I would have been very suspect about the state of tune causing a no-start condition.
The car went from apparently no problem to a no-start and the odds of the tune-up (a bit of a misnomer) causing this is about zero.
The no-start or dying could well be the distrbutor; or something else. (fuel pump for instance)

Back to the neglect issue, these things do snowball and many, many problems can be created due to ignoring simple basics.

That main relay controls a lot…fuel pump, ecu…etc… If it isn’t working neither is the vehicle. I’d like to see someone look into that. Throwing a part per code at the car is PURE folly…and a way shops use to validate the need for a part…they should know better…maybe they do know better and needed a boat payment…

I was going to say the car hasn’t been neglected. However, all I can really attest to is that we have taken it in for regular maintenance – I have no idea whether anything was actually done. We go by the recommendations in the manual in terms of when we take it in and for what. The need for a tune-up seemed odd because we had it tuned up when we had the timing belt replaced so while it hadn’t just been tuned, it certainly shouldn’t have been so in need of a tune up that it wouldn’t start at all.

The first mechanic was an independent, local shop that was highly recommended. The first shop replaced the plugs and air filter, checked the cap and rotor and listed as OK. Then when they test drove it the check engine light came on for the first time. It through a P0131 code, which is when they changed the O2 sensor (it says B1 S1 if that means anything.) The second shop scoffed at the idea that needing a tune up would make a car not start.

The second time it died whle running, no check engine light and no code. They said it had fuel pressure but no spark. They checked the distributor and said it had failed. The replaced it along with the cap and rotor.

Then the check engine light came on again and it threw out a code PO420.

FYI, the shop we used to go to and which did previous maintenance work has gone out of business, which is why we are in search of a good mechanic.

Honestly, this one looks to me like a a couple of coincidences. First, as ok4450 mentioned & one of the shops “scoffed” about, a car won’t go from running fine to not starting because of the need of a tune up. It will also not have a no start problem because of a P0131 code/problem.

The thing that likely ties most things together is a distributor failure. Depending on the failure mode, that could leave you with a no start one minute, and then running fine, and then stalling.

It is also possible for this to damage your catalytic converter from having unburned fuel entering it. However, the P0420 code does not mean that you need a new catalytic converter. All it really means is that the readings your rear O2 sensor (post-cat) is sending to the computer look too much like the ones from the front sensor (pre-cat). This will be the case IF your converter is bad. But it can also be the case for other reasons, such as a problem with the sensor itself or an exhaust leak. The best thing to do first with the P0420 is to have the code cleared and then keep driving to see if it comes back. If it does come back then have a look at this: - and ask the shop what they have done to verify that the code is being caused by a problem with the converter itself. I wouldn’t let anyone replace it until they could explain to me exactly how they know that it is the problem. I’d also go so far as to ask if they’ll credit the costs if they’re wrong about it.

So, in sum, the starting/stalling could very well have been from a failing distributor. The P0131 is probably a complete coincidence. The P0420 may be a coincidence or may be related to the failing converter.

That’s my best guess of your story. None of it is abnormal given the age & mileage of your vehicle. If it helps you any, my auto headaches - like lots of other bad things - tend to come in groups of three.

Thanks. I wondered if the distributor could have caused the problem with the cat, but the mechanic insisted it was probably a coincidence. Who knows? My frustration is with the notion of reading the codes and replacing parts without looking for an underlying issue. It’s possible the first shop replaced an O2 sensor needlessly because it was giving bad readings due to the distributor failure, right?

I’m taking it to a third (I know, crazy) shop next week. It’s (again) highly recommended and independent. But given the miss on the distributor failure I don’t feel comfortable with the first shop.

I understand that it’s getting up there in age and in miles and I fully expect to pay for repairs. What I don’t expect is to pay for repairs and have parts of the same system keep failing in succession. But the rule of three works for me, too, so maybe I’ll get this fixed and have a few more trouble-free months!

I would lean toward the P0420 being a coincidence - and keep in mind that it only means that you might have a cat problem. The reason I lean toward coincidence is that IF the cat really was damaged and IF it was from too much fuel entering the exhaust (owing to misfires from a failing distributor), then it would have been running noticeably poorly for quite some time. You just report that it suddenly wouldn’t start one day but imply that it always ran perfectly well up to that point. So if it has been running oddly for a while, then you might elaborate.

But I’d also remind you that the best thing to start with on the P0420 code is to reset it & wait to see if it comes back. You already seem to have in your mind that you need a new converter. I’d also emphasize that I can only guess about things based on what’s in this thread.

The P0131/O2 sensor replacement & distributor are not related. If there was reason to believe they were I would have said so rather than calling it a coincidence. P0131 is a straightforward circuit code regarding the PCM getting an extended low voltage reading from the sensor. That’s pretty much a wiring or sensor issue. Even IF a distributor problem was causing too much fuel in the exhaust, that would produce an O2 sensor reading on the HIGH end of its voltage range - not on the low end. So no - the P0131 wasn’t a symptom of the distributor issue. At least, I can’t think of any plausible link. The only thing I can say about it in terms of replacing the sensor is that my advice on initially getting a P0131 would be the same as the P0420 - to start by resetting it & wait to see if it comes back.

I’m with Honda Blackbird.
I hate to recommend the throwing of parts, but:
The distributor has been changed, so that leaves the main relay and the ignition switch, neither are expensive.

We reset the light and it came back on a day later. So I know something is wrong. I’m going to ask the mechanic how he knows for sure it’s the cat before I have it replaced. Yes, the car was running absolutely fine until it wouldn’t start. There was no check engine light on at all until they replaced the spark plugs.

Should I insist on a Honda cat if that’s what we do or is aftermarket OK? I don’t want to spend unnecessary money but I also don’t want to get cheap and end up causing more problems.

I don’t know enough about replacement cats to comment on whether to replace with a genuine Honda or not. I do know that I have seen reports of certain cars being “picky” about that. I would probably find a dedicated CRV discussion board or two and find out about the experience of other CRV owners.

How many miles on this car? As long as it was running okay, I would not spend another dime on it until it fails an emissions test…$900 for a distributor? What a deal…

The distrib costs about 145 for this vehicle…and the main relay is like 35 bucks… If that relay did its magic it would cut power to the distributor…it will run one second and then strand you the next. Hate to beat a dead horse here but did anyone look at the main relay? Cant tell you how many x I got a Honda from a customer…who had been “everywhere” and fixed his issue in minutes…

I don’t know why anyone is still talking about relays. There is no current report of the car not starting or running. Only a report of a current P0420 code.

I assume I am theone talking about relays…thats obvious no? We arent talking about the car not starting anymore? LOL…I gotta reread where we are at. Sorry, new yrs eve is still blurry for me…I am not as “on point” as usual… LOL…sorry

The OP reported a no-start and stalling while running.
The OP has not reported a fix for those problems.
I’m also talking about relays.

A little story:
Last summer walking to my car in a grocery store parking lot I encountered a woman and 3 kids is a battered looking '90s era Accord.
Cranking and cranking, no start. I offered to help.
Asked her to step out of the car. I reached in and gave the left underside of the dash a firm whack with the palm of my hand.
Started right up.
Told her to go get the main relay replaced.
She was quite impressed.

LOL…THATS THE RELAY I’m talkin about…so you know after all Eh? I thought/was hoping you would know bout that being a circuitsmith and all.

Hey Circuit…I have an electrical diagram of something that is supposed to bypass the Vats system in GM…would you be able to interpret it for me…offline? The diagram is not marked properly in my opinion…so I am having a hard time knowing what I am going to be cobbling up here in this instance…