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Catalytic Converter Question

The “check engine” light on my 2002 Toyota Camry (145,000 miles) came on (we’ll say on Friday) while on a 3-hour car trip. I took it to my trusted local mechanic on Tuesday to have it checked out. I was informed that the problem was that the catalytic converter was going bad and would (eventually-within weeks) need to be replaced (sadly, a costly repair). I was assured that the oxygen sensors were checked and that the problem lay solely with the converter (the 1st one that comes off the engine). Mechanic said that I could wait “a little while” but that I also risk damaging the secondary converter (further down the system), and even risk other engine damage if the converter breaks apart (inside) and gets drawn up into the engine (a rare occurrence but still possible). Thursday, the “check engine” light went off and has remained off (it is now Saturday). What do you recommend I do now? Thanks!!

Drive on until the light comes on again.
In the meantime make sure all the maintenance is up to date.
How long since the spark plugs were changed?

I agree with circuitsmith. If the light is off now drive it and see what happens after checking your maintenance records. Also I have never heard of the internals of a converter breaking apart and getting into the engine. They are in the exhaust which is outflow not inflow. I have seen them break apart and block the exhaust system which causes a large loss or intermittent loss of power.

Without knowing the mechanic, I question the results of oxygen sensor tests. Just because it is switching and putting out voltage within specs does not mean that it is reacting quickly enough to work properly with your fuel injection system.

The only indication that your engine computer has regarding the performance of your catalytic converter is the signal it is getting from the rear oxygen sensor. If that sensor is original, I would absolutely replace it as routine maintenance before considering the purchase of a new catalyst. I recently had a catalyst fail at 140k miles, but it is much more common for them to go twice that far unless there is some other problem with the engine.


4 cylinder?

If you have the 4 cylinder, this is food for thought.

Also, in some of these situations, the oxygen sensors are the real culprit.

Perhaps you can have the dealer update the ECM software. Some independent shops aren’t set up to do that. Once that’s done, clear the code and let the monitors run to completion. Your mechanic will know what I’m talking about. If that doesn’t work, it’s time to consider thoroughly testing the O2 sensors and the cat.

Oxygen sensors have a design life of 100K miles. At 142K, yours are due replacement should the light return…All this can be deferred until your next emissions test is due…

My 2002 Outback check engine light came on indicating a failing catalytic converter at around 125,000. My mechanic said not to worry about it. The light has been periodically on but mostly off for the same thing. It now has 285,000 miles on it and still runs great. Glad I didn’t waste $800 on that.

@iafn may I assume you live in a state with no smog inspections?

Our inspections are done by the Check Engine light being on. It rarely is.

@Iafn ln many ways I feel this is superior to tailpipe testing. I will assume the smog technician connects to your 16 pin DLC and if there are no codes and all the monitors are set, you’re done.
Is that right?
If so, it’s a lot quicker and (hopefully) cheaper. OBD 2 does a pretty good job of detecting malfunctions nowadays.

There’s a slight chance the CEL bulb burned out. Make sure the CEL comes on when you turn the key to “on” but before you start the engine. If so, and all your routine engine maintenance suggested in the owners manual is up to date, I think you are good to go.

@GeorgeSanJose no offense, but in my professional experience, the only reason one of those warning bulbs didn’t turn on was when somebody had physically removed them. I know it’s theoretically possible . . .

Physically removed them?? Why would anybody do that?? (: (:

db … You seem pretty savy. Are there really two cats on this car? Are they side by side, or one upsteam of the other? I can see a side-by-side config for cats, one for each exhaust bank, but for the life of me can’t understand why they’d be configured in series.

And isn’t it within expectations for a cat to fail at 145k? Or is failure at that low of mileage unusual for this engine?

You are absolutely correct, a burned out CEL bulb would be very unusual.

@GeorgeSanJose while I don’t know what engine OP has, perhaps this will help you understand the many possible cat configurations.

It is NOT within expectations for a cat to fail at 145k. Many cars are on the same cat their entire lives. Cats often die because of abuse (leaking injectors, blown headgaskets, misfires, etc)

Thanks, it looks like a common config for v6/v8 there are two special purpose cats in parallel, one for each bank, called “warm up cats” , these two exhauststreams combine to one, and go through a common three-way-cat. This config must improve the emissions. Good info.

Somewhere around 150,000 miles is when Toyota oxygen sensors are likely to fail. You’re in that range but we don’t know the code that the mechanic found. I’m talking abut the forward oxygen sensor.

Somewhere around 150,000 miles is when Toyota oxygen sensors are likely to fail.

Where did you pull that stat from??? Gee…I’m about 70k miles past due. And since I have 4 of them…I’m well past the statistical average.

The ONLY O2 sensor I had replaced was when the garage that replace my exhaust accidentally destroyed it. They admitted it and put a new one in for free. All vehicles well over 150k miles…most past 250k miles…some past 300k miles…and at least 2 past 400k miles without ever replacing an O2 sensor.

Thanks for the great info! The CEL light is still working as it comes on briefly (as do the other “dummy” lights) when I start the engine, but then it goes off. I’ll change the oxygen sensors and get a tune up (new plugs, etc) too to be on the safe side and wait and see how it effects my issue. The Camry is a 4 cylinder. I am not required to have an emissions test in my area…just don’t want to mess things up leading to higher repair bills later. Looks like the consensus is to take care of the regular maintenance issues & oxygen sensors and not worry about the catalytic converter unless the light goes on (and stays on) again or the car’s performance is effected.

@Krash1976 I would update that software before buying new O2 sensors. Updating the software might cost you a c note, but the O2 sensors will cost way more than that.

This would be my plan of attack, in this order:
Update software
Test and, if necessary, replace O2 sensors
Test and, if necessary, replace the cat