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My check engine light was on for some time. My mechanic was monitoring it until finally said that my catalytic converter needed to be replaced to pass inspection. I just picked up the car and it seems to be noisier than before the replacement. The noise is coming from underneath the car near the driver seat. Will this noise go away after some driving or is it another problem that is lurking around? Please help, thank you.

Answers from the Automotive Experts

Amanda J. Pierce, MBA SubaruBea, Thank You for writing into AskPatty!! When the mechanic replaced your catalytic converter, they may have not tightened the collector gasket bolts. There are exhaust gaskets that seal joints where the exhaust pipe joins the header. I would return to that mechanic and have them check the gaskets! Hope this helps!! A. J. Valle

Judy Curry, Co-Founder and Vice President of Marketing at Currys Auto Service Subarubea, Assuming that your check engine light is no longer illuminated, it sounds like it could simply be the heat shield. It might have been misaligned during the install of the converter. Your Technician should look at and correct the problem for you at no charge. Thanks for your question! Best, the Curry's Auto Team

Kristin Brocoff, Director of Corporate Communications at CarMD.com Sorry to hear about your vehicle. Catalytic converters are pricey parts that don't often need to be replaced. Are you sure it wasn't a smaller problem upstream like an oxygen sensor or spark plug? If left ignored, these smaller problems can cause catalytic converters to fail. You may want to run a quick diagnostic scan on your vehicle with a code reader or system such as CarMD to diagnose the problem. Also, any time you have a repair (pricey or not) and have problems, noises or any type of concern shortly after leaving the shop ... please immediately let the mechanic know. A reputable tech will want to ensure it was fixed properly the first time. Kristin Brocoff CarMD.com Corp. www.CarMD.com

Lori Johnson, Owner and Instructor at Ladies Start Your Engines Dear SubaruBea, There's no reason it should be louder. I would take it back and ask them to take a drive with you so that they hear the same thing you do. I would also ask why the catalytic converter went bad. This usually only happens for a couple reasons. One, you have a leaky fuel injector that's dropping raw gas down through the system and getting burned in the converter, causing it to go bad. Or two, the catalytic converter hit something in the road and was damaged. It's possible that if they didn't fix the problem that caused it to fail that it could happen again. Take a look at this website that explains what can happen. http://auto.howstuffworks.com/question482.htm I have a vehicle that is 24 years old and I still have the original converter. They typically last the lifetime of the vehicle. Good luck. Lori Johnson www.ladiesstartyourengines.com

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