Troubleshooting noise and vibration on your Cat Shield™

Miller CAT’s guide to addressing rattling/noise

When properly installed with the correct hardware, the user should not experience any significant noise or rattling. Our products have been designed to provide your car with optimal clearance to prevent your shield from coming into contact with your exhaust.

To properly address any noise you may hear, there are two conditions that must be met.

  • Your car must have the original catalytic converter installed. We cannot guarantee any fitment or noise-free operation if your vehicle has an aftermarket converter.
  • Your shield must have been properly installed. This includes the use of Miller CAT provided hardware and following the instruction guide and proper placement of the shield. Installers must use all the spacers, rubber dampeners and hardware to ensure proper fitment.

*If your shield required rivet nuts, make sure the rivet nuts were fully crushed and are not loose.

If you meet these two conditions, please see the following suggestions.

Most common solutions:

Prius Gen 1/2 (2001-2009)

Replace exhaust hangers. Any vehicle that is older than 10 years should have their exhaust hangers replaced. Exhaust hangers keep your exhaust system from swaying too much. For Prius Gen 1/2 (2001-2009) owners, it is highly recommended that you replace the exhaust hangers. They are the cheapest and simplest solution to any rattling.

Prius Gen 3/C/V (2010-2019)

Verify all hardware was used. Ensure the shield was installed with the provided spacers and rubber dampeners.

Check the bends and recirculation hose clip. On the Gen 3 (non-Prius C/V), make sure all the 3D features (bends at the rear of the shield and bridges running along the recirculation hose) have been properly bent. There is also a clip on the hose that can be adjusted to prevent any contact with the shield.

Replace exhaust hangers. Replacing exhaust hangers can help ensure there is not excessive swaying of the exhaust system that could come into contact with the shield. 

Prius Gen 4 (2016-2022)

Check the orientation of the shield. Our Gen 4 shield is symmetrical and users can incorrectly install the shield with the wrong side facing down towards the ground. A tip is that the M logo should always be on the right side of this shield when the owner is looking at it. The lip of the shield should also be facing toward the rear of the vehicle. 

Honda Element

Check to see if the converter is an original converter. Any aftermarket converter is not guaranteed to fit properly due to the variance in the bends with aftermarket parts.

Replace exhaust hangers. New exhaust hangers will keep the exhaust system from excess movement.

If your vehicle still experiences vibration, please contact us at support@millercat.com.