I need to emissions test my car?

2013 TOYOTA COROLLA
175,515 MILES • MANUAL
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RLPETERSON78
  • MEMBER
  • 131 POSTS
I just solve some EVAP codes on my car. I drove the car over 100 miles and attacked my scanner. There were no engine codes, but the red light was on due to O2 sensors and Catalytic converter. I put my live data on and saw there was no response in my 02 sensors, no voltage at all. Does this mean that my O2 sensor are bad?
May 20, 2026 at 1:08 PM
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STRAILER
  • AUTOMOTIVE REPAIR CONTRIBUTOR
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No, not automatically. No O2 sensor voltage on live data does not always mean the O2 sensors are bad.

Also, on this car the upstream sensor is usually an air/fuel ratio sensor, not a normal old-style O2 sensor. Many basic scanners do not show it as a normal 0.1–0.9 volt switching sensor, so it can look like there is “no voltage” even when the sensor is working.

The red light on the scanner for O2 sensor monitor and catalyst monitor usually means those emissions monitors are not ready, not necessarily that the parts are bad. Here is a guide to help you reset the monitors.

https://www.2carpros.com/articles/how-to-reset-an-engine-computer-monitor-program/

Please go over this guide and get back to me.



May 20, 2026 at 4:42 PM
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