Toyota Yaris Catalytic Converter Rattling Noise – Possible Causes?

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Toyota Yaris Catalytic Converter Rattling Noise – Possible Causes?

Hi all,

I’ve started hearing a rattling noise coming from under my Toyota Yaris, especially when idling o r driving at low speeds. I’m wondering if it could be a sign that the catalytic converter is damaged o r clogged.

For those who’ve dealt with this before, did you experience any unusual noises? How did you diagnose the catalytic converter as the problem, and what was the solution?

Thanks for sharing your experiences!

Sirat Ul Jinan asked on 28 Jan 2025 17:08:56 pm

1 Answer

42 views |

Car Mechanic Expert - on 28 Jan 2025 17:15:46 pm

A rattling noise coming from under the car, especially at low speeds o r idle, can indeed be a sign of a damaged o r clogged catalytic converter. The internal components of the converter, such as the catalyst material, can break loose and cause a rattling sound when they shift around.

To diagnose the catalytic converter as the issue, there are a few steps you can take:

Visual Inspection: Check for any visible signs of damage o r wear on the converter. A cracked o r physically damaged converter could be the cause of the noise.
Performance Check: If your car is also experiencing poor acceleration, reduced fuel efficiency, o r power loss, it could indicate a clogged o r failing converter. The noise, combined with performance issues, points strongly to the catalytic converter.
Rattle Noise: The noise might be most noticeable when idling o r driving at low speeds, as the loose material inside the converter moves around.
Check Engine Light: If the check engine light is on, the O2 sensors may be reporting poor performance o r inefficiency in the catalytic converter. A diagnostic scan can help confirm this.

Once diagnosed, the best solution is often to replace the catalytic converter, as repairs o r cleaning are typically temporary solutions. If youre hearing this noise but arent noticing performance issues, it could still be worth having a mechanic inspect it, as a malfunctioning converter can worsen over time.