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Q: P0421 code and wheel bearing

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Check engine light came on almost 2 years ago.. threw this code, I got code checked then cleared and it stayed off for about a year.. came back on and since it's been on,its been staying on for a long time, then goes off for a few days, then back on again... is it the catalytic converter for sure? I need to get my car inspected and am worried it won't pass with the light on. I cant afford to get anything fixed right now and trying to figure it all out.. also have a wheel bearing question.. when I drive on Highway and turn a corner I hear an almost like rubbing/grinding type noise (hard to explain the noise)... but also when I slow down to stop or am going slow in a school zone my car kinda bounces, (new issue noticed) I have a bald tire which I need to change and also haven't gotten my tires rotated or balance like ever.. thinking that's the issue? Sorry don't want to sound like a helpless girl cause I know more than most..but not enough clearly. Thank in advance for any help! Xoxo

My car has 121000 miles.
My car has an automatic transmission.

A: Hi there. The P0421 error code typically in...

Hi there. The P0421 error code typically indicates that the catalytic converter is wearing out and needs to be replaced. However, it could also be sensors that are damaged sending false information. In regards of the wheel bearing, that rubbing or grinding sound when you turn (or go over a speed bump in some cases) is probably the wheel bearings that are starting to lose some lubrication and beginning to wear out.

That's usually the best indicator that you should replace the wheel bearings before they cause more damage. About your tires, yes, having them rotated will help reduce the wheel wear significantly. You should have at least (2) tires replaced on the same axle at the same time, then 4,000 miles later, replace the other two tires and begin a rotation program (or have it done the same time as oil change). When you have a rotation or oil change done (or both), have the mechanic diagnose the Check Engine Light so that this issue can be corrected as well.

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