2000 Toyota Corolla P0420 and steering wheel shakes

140,000 MILES • AUTOMATIC
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ACAMPAN
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Hi. Thank you for this great service!

My car has a P0420 code. I've heard a P0420 code can be other things, not the catalytic converter, so I've been looking for other things that could be the problem. Car has been idling high, so started there.

I changed the spark plugs, they were worn out and needed replacing.

I cleaned the mass air flow sensor - fixed car hesitating on acceleration. The throttle body/idle air control valve were cleaned by my mechanic.

The car still idles slightly high, but it's much better. If I just turn the car on, it'll idle at the correct amount (750 rpm's). If I've been driving and I park, it'll be right at 1,000 rpms.

The car has an aftermarket converter already from the previous owner, but I want to address any other problems it might have before replacing it as it might not even need replacing.

I also have a K&N air filter that.

What could be causing the P0420?

Also, I just had a balance and rotation and the steering wheel shakes at 65+ mph. The balancing was rechecked 3x and is fine, other mechanic checked suspension components and says they're fine. Car is slightly out of alignment. What's causing the steering wheel to shake?

Thank you!

2000 Toyota Corolla LE
Sep 7, 2014 at 11:51 PM
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HMAC300
  • ✓Experienced Mechanic
  • 48,601 POSTS
p0420 code is either a bad catalytic converter or an air leak prior to converter on exhaust system with your mileage it's probably a converter.or maybe an O2 sensor but I kin dof doubt it
Sep 8, 2014 at 12:26 AM
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