Catalytic Converter

[ryansride2017]

I have a 2003 Corolla that just started throwing CEL lights periodically. The codes refer to "abnormal catalyst efficiency". While I'm sure it could be the O2 sensors, based upon the age of the catalytic converter (never been replaced) and the slight odor under heavy load, I believe the converter is toast. The car does not burn any oil and otherwise runs fine. My question is this: I frequently hear of episodes of catalytic converters blocking up, but does it only block up if it is associated with burning oil? Will an otherwise healthy engine, where the catalytic converter dies of old age, block a catalytic converter? I live in a portion of the state that does not have emissions. I bought the car as a high mileage beater and would like to put as little money into it as possible. I can put up with the CEL, but will I see any other harm from an expired catalytic converter?

 

[Dave Hess]

How many miles ?

Did you see a drop in gas mileage after the CEL came on ?

You could hollow out the cat if its clogged.

 

[ryansride2017]

152K. With the winter gas and the type of driving I've been doing, it's hard to tell if there has been a mileage drop. If there has been, it hasn't been much.

 

[Cause4Alarm]

converter= toast.........if it's getting flooded with oil it can clog though, but this is common to turbos letting go. the usually burns off what little oil gets in, but very rich afr's can cause the sub straight(brick) to melt as unburned fule then burns in the cat

 

[Cause4Alarm]

oh and if it is clogged power, driveability, and fuel mileage will all suck

 

[ryansride2017]

In reading the Corolla forums, converter failure at this mileage is somewhat common. The vehicle doesn't burn oil, so what else would cause it to clog? I'm hoping since the car is otherwise running well, I can continue to run it without anything more than a CEL on.

 

[ryansride2017]

Originally Posted By: Cause4Alarm
oh and if it is clogged power, driveability, and fuel mileage will all suck


The car doesn't drive any different. It's not stalling or sputtering.

 

[The motor guy]

My modo is if it still drives fine then keep driving. Atleast until inspection time comes.

 

[punisher]

Originally Posted By: ryansride2017

The car doesn't drive any different. It's not stalling or sputtering.


Well, then it's not clogged, it just fell below the threshold of effectiveness your PCM thinks it should have.

Converters fall off in efficiency everytime you drive it. Thats normal. New cats have a lot of excess capacity built in to them just for this reason. Sometimes the stuff you run through the engine that makes it into your intake and gets burned contributes to a shorter lifetime. Pre SM oils, a lot of gas additives, some intake cleaners, oil additives etc contribute. All it takes is a tiny amount of deposits to chemically kill a cat.

As far as actually clogging/melting a cat, thats tougher. Some cats disintegrate on their own, just bad design/materials/construction from the get go.(Certain early V6 Contour/Mystiques come to mind)

Missfires- big cat killer. That is the reason (the only reason actually) why you have mandatory missfire monitoring on EEC-V systems. Contrary to popular belief, running rich does not cause cats to overheat/fail. To overheat a cat you have to have unburned fuel, as well as excess O2 in the exhaust. Rich running engines have no excess O2; however, missfiring engines do, hence the missfire monitor.

High mileage cats die, it happens. I replaced a fair amount of them.

 

[AdRock]

Have the O2 sensors ever been replaced? If not, I'd try replacing them and reset the ECU to see if the light comes back on.

I've fixed several cars over the years that had sensors going bad causing them to make the engine run rich or lean. Which in turn jacked the converter and made the rear sensor set a CEL saying that the converter wasn't working properly. They replaced the converter but not the sensors and basically ruined a new converter. They ended up paying for 2 converters and 2 sensors when 2 sensors the first time would have done the trick.

Just some food for thought.

 

[MarkM66]

Originally Posted By: ryansride2017
Originally Posted By: Cause4Alarm
oh and if it is clogged power, driveability, and fuel mileage will all suck


The car doesn't drive any different. It's not stalling or sputtering.


I would not worry about it any further, and keep driving.

 

[Vikas]

If you are serious about doing *anything*, let me know. I have few suggestions. Trust me, I have had too much experience with P0420/P0430 :-(

Also please indicate your mechanical capability and the dollar amount you are willing to spend.

- Vikas

 

[lexus114]

try using some 89 octane fuel. it may sound stupid, but I would be willing to bet it will get rid of the problem. as long as everything else is ok.

 

[mechtech2]

I'll take that bet.

 

[wiswind]

The oxygen sensor(s) would be the sensor(s) that is downstream.....after the catalytic converter.
If you have 1 catalytic converter, you will have 1 downstream sensor.
The downstream sensors are slightly cheaper than the catalytic converter.
Ease of replacement is dependant upon how rusted things are.
The DENSO OE style (direct plug in) is $53.79 on the rockauto.
It is the "downstream" sensor.

 

[ponderosaTX]

There is a commonly used maintenance procedure using spark plug anti-fouling spacers that usually eliminates cat CEL codes if the cat is unobstructed. See http://forum.mpvclub.com/viewtopic.php?t=22162.

 

[Vikas]

Two chemicals which have been reported to work

CRC Guaranteed to Pass
Cataclean

Both these chemicals are available at Amazon or your local auto parts stores such as NAPA.

CRC is reputable company. Cataclean is by some fly by night operation. However, my NAPA carries it and when asked, he said it works.

I personally have the O2 extenders but if I had known about these chemicals, I would have tried them before doing the extenders.

- Vikas

 

[dailydriver]

Originally Posted By: Vikas
Two chemicals which have been reported to work

CRC Guaranteed to Pass
Cataclean

Both these chemicals are available at Amazon or your local auto parts stores such as NAPA.

CRC is reputable company. Cataclean is by some fly by night operation. However, my NAPA carries it and when asked, he said it works.

I personally have the O2 extenders but if I had known about these chemicals, I would have tried them before doing the extenders.

- Vikas


I was actually going to start a new post (and may still yet) asking about the Cataclean stuff, in the gas additives forum.

As far as you know, are these treatments so powerful that they would cause wash down and subsequent fuel dilution of the oil??

 

[Vikas]

I don't think so. I mean the amount of the cleaner you are adding is so little that it would be a miracle that it even (allegedly) works

 

[dailydriver]

Originally Posted By: Vikas
I don't think so. I mean the amount of the cleaner you are adding is so little that it would be a miracle that it even (allegedly) works


That's what I was wondering about, since the Cataclean stuff actually claims to clean out the catcon AND clean off the O2 sensors (to the point of being able to turn off and keep off the MIL/SES/CE dash lights!), whereas the CRC stuff (according to the box at least) only claims to super clean the valves, ports, and combustion chamber in general. NO mention at all of actually cleaning/scrubbing the catcons/O2s.