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Q: Failed a smog test

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I took the car to get a smog check and it has failed the NO part the first time and the HC the second time. I took it two different mechanics and one tells me its the catalytic converter and o2 sensor. The other one says the engine is burning too much oil. I did the oil change about 2 months ago oil seems to be doing okay. This car has had the catalytic changed 4 years ago by my brother the first time it failed the smog. Im just wondering if to change the catalytic converter and 02 sensor would make any difference for the smog. I have no other issues with it. The check engine light is not on.

My car has 175000 miles.
My car has an automatic transmission.

When the catalytic converter and the O2 sensor are not working properly, the car will fail a smog test every time. I would recommend changing the catalytic converter and the O2 sensor in order to get your car to pass smog.

However I would investigate further the issue of the catalytic converter failure in such a short time of four years. This is not particularly normal for most cars. In fact most cars never have to have them replaced. This suggests you may have other issues going on relating to the fuel combustion process.

If you’d like to get this fixed, I would suggest having an expert from YourMechanic come to your home to diagnose this issue and replace your catalytic converter and O2 sensor as necessary. Best of luck.

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