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Replace Catalytic Converter and O2 Sensor or get a new car?

I moved away for a few years and recently moved back and needed a car so I thought I would try and get my 2002 Toyota Solara up and running again even though it hadn’t been driven in 3 years. I spent around $1300 worth of tune-up on it: new battery, new two front tires, new windshield wipers, new spark plugs, coolant flush, fuel injector, flex pipe (because there was a leak), oil change… I looked up what else needed to be done and someone mentioned air filters and everybody said it was super easy to replace on your own. So I got an engine air filter from the dealership and replaced it but it turns out that I had put it in wrong and it clogged the catalytic converter. The quote is around $800 for a new O2 Sensor and catalytic converter. I’m heartbroken after having already put so much money into it. I know the car wasn’t worth much in the first place but it only has 171K miles on it and I don’t plan on driving it that much anyway. I really didn’t want a new car and make car payments but this car has given me so much headache… I’m torn over what to do… if I had known repairs were going to be this much I wouldn’t have bothered… any thoughts from the community?

You’re going to have a hard time convincing me that an improperly installed air filter is going to clog the catalytic converter.


Many, many catalytic converters are replaced incorrectly. I’d replace the O2 sensor and see if it make the check engine light go out.

Consider this. $800 is 2 car payments. One O2 sensor is less than one car payment.


How do you know the cat is plugged? Is the check engine light on? What codes were created?

I also can’t see how the wrong air filter would have caused this.

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do you have a 4cyl motor or v6? the 4cyl has a much simpler exhaust, basically 1/2 of the v6. shop says to replace which cat exactly?

Agree that an air filter installed incorrectly (or a dirty air filter, or even running the engine without an air filter) shouldn’t clog the cat converter. What exactly is wrong with the car’s performance? Did you get it running after it was in storage? If so, is it running poorly now that you have the failed cat and 02 diagnosis, or is the check engine light on but it runs ok?

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I was thinking the same thing. I’m also amazed you were able put it in any other way then it should.

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Well, after I installed the air filter, the air hose was loose and I didn’t know it. I started the car and the engine sputtered. I checked under the hood and saw that the hose was loose so I put it back and it was fine. But the check engine light did come on, the car started vibrating when I was idle, and I felt a jerk when I was accelerating. I checked under the hood and the hose was a little loose again… not sure if that was what caused the damage. I took it to the shop and that’s what they told me… that I put in the air filter wrong, but the paper they gave me said I didn’t properly put in the hose… It was running fine after storage, was a little loud because I had a leak but I got it fixed and it was fine again. But I didn’t really drive it until after I changed the air filter so I can’t tell if this was going to happen anyway.

I have the 4 cylinder. They didn’t tell me which cat. I thought there was only one… it said code P0420 came up.

I know just paying the $800 will be cheaper than getting a new car but I don’t want to keep making $800 payments if repairs this expensive keep coming up…

I’m not convinced you have a catalytic converter or O2 sensor issue. There’s no relationship between improperly installing an air filter and “damaging” the CC.

I’d take it to another mechanic for a second opinion. Sounds like this first one needed to make a boat payment.


+1. It’s a good idea to get a second opinion when you have a potentially major repair anyway…but add my name to the chorus of posters who aren’t buying the idea that an incorrectly installed air filter will damage a Cat or O2 sensors


I agree with the others. You did not wreck your cat by installing the air filter wrong.

What exactly do you mean by “air hose?” Does it look like this:

or this? (the thing the hand is holding)

If it’s the latter, then that hose slipping off induces a vacuum leak which can trip the catalyst code. Replace the hose (with a new one and a new clamp too, don’t just put the old one back on) and reset your codes and see if the code comes back. That’s a whole lot cheaper than replacing the cat.

Solaras were if I recall based on the Camry, and those were very good cars. There’s no particular reason you shouldn’t get years of good service out of this vehicle, so if you don’t want a car payment, I recommend dealing with the problem. That will involve either fixing it yourself, or taking it to a different mechanic. I don’t like it when mechanics see P0420 and immediately without further checking say “yep, it’s your cat, gimme a lot of money.” That’s a sign that they’re either bad diagnosticians or that they just want to perform an expensive service without worrying about whether or not it’s necessary.

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Post the check engine codes. You are going to have two O2 sensors on the car at least. One upstream and one downstream. The one downstream is a check to see if the catalyst is still working. The one upstream has the most impact on driveability and fuel economy.

These were $50 each on the last car I replaced them on. Some use a more specialized sensor and I don’t know what you have. If they haven’t been replaced yet, they are probably due.

I understand being frustrated because you have already dumped in lots of money but you would hate to give up maybe $100-200 from having it fixed.

This. This. And more of this.

Now that the air intake hose has been installed properly, erase the fault code and see if it comes back, it probably won’t.

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I was thinking the same thing. They only thing I’ll add is that you can ruin a cat pretty fast if you are running it with a misfire, depending on what hose, etc. Mine got red hot in about 15 minutes in the garage and that’s all she wrote. Assuming this didn’t happen though, clear the codes, fix the hose correctly, and see if the codes come back.

The thing in the blue circle came loose.

I did feel a jerk… that’s the same thing as a misfire right?

If the catalyst converter is clogged, could it cause the engine to stop running? When the mechanic called me about my car, he said I don’t want to be driving it with a clogged cc because that could happen… so it makes me wary of driving it around…

Take it somewhere else for a second opinion, I’m getting a bad feeling about that shop. Check with friends, relatives, Yelp, etc to find a reliable shop near you. Have they told you the codes?

Did they tell you that the air leak damaged the cat? If so, I thing that was nonsense to scare you into spending BIG $$$$.

That’s the Positive Crankcase Ventilation hose.

That hose allows crankcase gases to drawn into the engine so that they can be burned.

I don’t see how that hose being disconnected could damage the cat.


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You don’t mention doing anything about the old gas that was in the tank. What happened with that?

I never drained it. The tank was almost empty when I started driving it again. I did mention that to the mechanic but they didn’t mention a clogged fuel filter or anything like that.