mpickard

Hi -

My O2 sensor has been failing about every 6-12 months. The check engine light comes on and the codes I extract are 1 and 43 - dealing with the O2 sensor. If I replace the sensor it runs fine for a while, but eventually the check engine light comes back on. The car usually stutters upon slight acceleration until the check engine light comes on, after which it accelerates fine.

I replaced the catalytic converter because I read somewhere that a bad catalytic converter can cause the O2 sensor to overheat. But apparently that didn't help.

I'm not sure what to try next. Thoughts?

Weakbyyou

could be burning oil and coating the o2 sensor. take your header off and check the 4 ports. one will prolly be covered in burnt oil. that is which cylinder is most likely gettting blow-by

mpickard

I have noticed that the O2 sensor do become blackened, so that would make sense. My spark plugs also come out oily. Oil leaks in from the top. Would that be related?

Jockone

The oil leaking in from the top is not related to the problem,it is the seals between the head and the valve cover causing that and is an easy fix.

plugger

If you are burning that much oil, you should be noticing it. How often do you have to top up your oil?

mpickard

I can smell oil burning after I turn off my car, but I haven't had to add much more than 1/2 quart of oil between oil changes (about every 4 months).

And I can see oil dripping down from the head cover gasket (or somewhere in that area). I've just been putting that leak off because I didn't think it was related to the O2 sensor issue.

plugger

It still may not be -- if you get even fairly minor leaks from the valve cover, oil can end up in the exhaust manifold, and even a small amount of oil will smell very noticably one that gets hot. But nothing to do with burning oil in the cylinders...

One thing you could try as an interim measure is to try cleaning the o2 sensor with (perhaps) carb cleaner or even brake cleaner, just to see if it can made functional again, rather than replacing. If you were going to toss it anyway, nothing to lose by trying...

But then it would still be a question of what's causing the fouling in the first place, if not burning oil. Perhaps your air filter needs replacing? If you are not getting enough air, you may be running rich, which wastes fuel and could cause carbon fouling.

Weakbyyou

good point about running rich. you need to figure out if it is just leaking oil or burning it to. could be 2 seperate issues. and good luck cleaning the o2 sensor, i have never been succesful, they are pretty sensitive

plugger

The other easy thing to look at is the good old PCV valve. It's job is to allow recycling of air with unburnt hydrocarbons in it to get burnt a second time, to make the exhaust cleaner. If that's not working, you will have dirtier exhaust gases, and that could contribute to fouling.

Replace it (and the grommet) anyway, just to be sure. Just a few bucks if you buy an after market part (undoubtedly dearer if you buy a genuine Honda part, though.)

The trick is to buy aftermarket when you can get away with it, and only choose Genuine Honda when you can't. I think this is one of those situations where you can (at least that's what i did last time I changed my PCV valve).

BTW, how's your fuel economy?

mpickard

My fuel economy is decent - 28-30 mpg (mostly highway). In the past, I may have gotten 30-32, but the decrease hasn't been drastic.

I'll try the PCV valve and grommet - that's cheap enough (like $8 together).

Isn't there a way to determine if my car is running rich? Can that info be read from a scanner? or do autopart stores carry tools to check that?

plugger

That's very good fuel economy, which adds to the puzzle.

If your O2 isn't working efficiently, or has degraded to the point where you throw an engine code, you will be running rich. That's the "safe" default the engine management computer uses when it can't see the the actual O2 level accurately becuase the sensor isn't working properly.

Running rich has a number of symptoms, including oily plugs as you've indicated, but it also means you usually get noticably poor fuel economy. The fact you aren't deepens the mystery a bit!

What brand/grade oil are you using? When did you last change it?

nus_dogg

When the ECU sets the code for the 02 sensor, it doesn't mean that the sensor itself is the culprit. Its telling you that there is something wrong in the circuit. If you can DIY, I'd start out with an DMM using the Haynes manual "checking" procedure.

mpickard

Yes, that puzzles me too. I can't complain about my fuel economy. I wasn't even complaining about replacing the O2 sensor every year, but they are failing sooner and sooner. I replaced with O2 sensor in Aug (so only 5 months).

I'm in need of an oil change - about 4500 miles ago. I replace it regularly though. I use 5W30 - have been using synthetic blend as of late. But I've been replacing O2 sensors for about 2-3 years now (3-4 sensors over that time period).

I have noticed increased oil drippage (and burning smell) as of late.

plugger

What trim level is your 93 Accord? LX/DX or EX/SE?

The reason I ask is that I notice TASauto have two different 02 sensor Honda part #s depending on the trim level: Part #2836529 is for LX/DX, part #2836530 is for EX/SE.

And just for (my) sanity check, the 93 has only one O2 sensor, in the exhaust manifold, right? (i.e., there is no downstream O2 sensor after the cat, as in later model of Accord.)

mpickard

Although, if I replace the O2 sensor, the car runs fine for an extended period of time (5-12 months)...

mpickard

It's an EX.

And I've only been able to find one 02 sensor. That was one of the first things I checked this go around, because I thought that maybe I was missing a sensor. So I took the "cover" off of the exhaust manifold, but there's NOT one there. There's only one before the catalytic converter. So, just the opposite of what you were thinking plugger.

plugger

Well, the position is different than on my Accord, but if it's before the cat, it's "upstream", if it's after the cat, it's "downstream". A car needs an upstream sensor for engine management, but a downstream sesnsor is much less critical, as it really is only there to verify that the cat is doing its job.

The main thing I was trying to verify is that you only have the one sensor.

As for the part # difference between the LX and EX, it's usually not that big of a deal, typically you only expect that to mean the wire length of the sensor might be different -- the actual sensor element should be exactly the same. But just out of curiosity, what sensor part # are you using to replace each time? Are you using a Genuine Honda part #2836530, the OEM part, or an aftermarket part?

mpickard

They are not genuine Honda parts. I've been using Bosch parts - is that OEM or aftermarket? The genuine part is like $180. That's pretty steep compared to $40.

plugger

I would think Denso would be OEM - that's the OEM for my 98 Accord, anyway.

Bosch is perfectly good quality, of course -- many people consider them the standard for O2 sensors.

A Denso unit (if that is the OEM) shouldn't be any more expensive than the Bosch equivalent.

Rockauto list the BOSCH Part # 15710 as the "exact fit" recommended replacement for your vehicle, $48.79. The DENSO Part # 2344209 they recommend as a universal, $40.89, and DENSO Part # 2344095 as the "exact fit" Denso, $72.79.

"Exact fit" just means you get the correct plug fitting out of the box, whereas "Universal" means you may have to cut and splice the wires of the replacement sensor to reuse your old plug fitting -- in general, the actual sensor component is exactly the same (but you probably knew that).

Just looking at some of the possible issues using non-stock sensors. Do you recognise the Bosch number above?

The fact that you are getting good mileage seems to suggest to me that your sensors are actually working well, even if your computer is detecting a diagnostic error. I'm trying to think how that might occur -- do you have a detailed description of the codes being thrown (1 and 43)? I'm wondering if that might be specific enough to give a clue.

Of course, nus dogg is completely correct in stating that an ECU code doesn't mean the sensor is defective at all, the error might lie in the diagnostic process itself (wiring or even computer error). But I think you have to elimate the more basic possibilities before heading down that track. It's also weird as you say that the sensors last a few months before the ECU throws a code.

To give you some idea, the last O2 sensor I replaced on my 98 accord was well past due -- about 10 years old, and over 150K miles. It wasn't sick enough to trigger a CEL error, but after replacing it, the fuel efficiency improved dramatically-- a classic case of a "lazy" sensor. The Bosch units are rated to last about 100K miles, I believe.

So you are clearly going through sensors at a rate well above anything normal.

mpickard

The descriptions I found for the codes (https://honda-tech.com/forums/honda-accord-1990-2002-2/check-engine-light-codes-cel-diagnostic-trouble-codes-dtc-malfunction-indicator-light-mil-1490107/) are:

1 Oxygen Sensor "A" (Primary) defective circuit or unplugged / defective sensor

43 Fuel Supply System defective or malfunctioning fuel supply system

Maybe I need to be paying more attention to the second code...

I was going to replace my fuel filter, just because it's something inexpensive to try (along with the PCV valve and grommet, which I'll try this weekend).

I noticed tonight that the hesitation upon acceleration has gotten worse (there was a faint hope inside me thinking I wouldn't have that problem this go around). The car shimmies on acceleration (sometimes pretty bad - to the point of the car losing all power, so I floor the pedal and it kicks in a 1-6 seconds later). If I keep the RPMs high (3,000 - 4,000) for a lengthy stretch of road, the CEL will eventually kick on and then the car accelerates normal.

TrungN

I've got the same CEL #1 code on my 93. I've checked the wiring and all seems to be ok. I'm not sure what's causing it, but my car runs like crap once that CEL comes on after 10 minutes of driving. Before that, it runs great. On my 2nd o2 sensor in a month.

curiousdude

maybe the problem is in your eCU?

uccjxe

If the sensor comes out all black, it probably is bad, but maybe next time you get the coes and it stars running bad, try a reset (disconnect battery for a minute) and see if the condition persists...

TrungN

o2 sensors are new, and I've checked the ecu by swapping in one that is known to be fine. Could the MAP sensor be causing this? I've been looking into EGR issues and was also wondering if a bad EGR solenoid could be the culprit. My EGR vavle is new so I know that's not it, and the EGR ports have been cleaned out with the intake manifold off.

91acco

Hi there
Just wondering if you ever got your O2 sensor problem figured out? I am having the same problem with my 91 Accord,and I haven't seen any good answers yet.