Why does the Prius sometimes fail emissions tests despite being a hybrid?

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Why does the Prius sometimes fail emissions tests despite being a hybrid?

Failing an emissions test can result from stored error codes, a bad catalytic converter, o r a faulty O2 sensor. Discussing how to prepare for emissions tests and fix common issues can help owners pass with ease.

Zarnish asked on 13 Feb 2025 12:38:43 pm

1 Answer

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Car Mechanic Expert - on 13 Feb 2025 12:46:15 pm

The Prius may fail emissions tests due to:

Stored Error Codes: If the vehicle’s computer stores error codes related to emissions components, it can cause a failure during the test.
Bad Catalytic Converter o r Oxygen Sensor: A malfunctioning catalytic converter o r oxygen sensor will likely cause the car to emit higher-than-expected levels of pollutants.
Evaporative Emissions EVAP Leaks: Leaks in the EVAP system can cause excess fuel vapors to escape, leading to failed emissions tests.

Preparation for Tests:

Ensure the car has been driven for a few days before the test to ensure it’s fully warmed up.
Fix error codes o r emissions-related issues before taking the test.