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2001 Hyundai Santa Fe AWD 2.7L V6 P0420 Code: Which O2 Sensor to Replace and Cat Repair Guidance

Model: 2001 Hyundai Santa Fe AWD 2.7L V6 Fault Code: P0420 Posted: 2014-04-04 11:48

My 2001 Hyundai Santa Fe AWD with a 2.7L V6 engine has triggered a P0420 diagnostic trouble code, indicating a catalytic converter efficiency issue. This model features three catalytic converters, and I believe the right one may be failing. A faulty oxygen (O2) sensor can contribute to catalytic converter failure. Since there are no drivability symptoms such as poor acceleration or stalling, I'm trying to determine which O2 sensor should be replaced—specifically, whether it's the upstream or downstream sensor—and whether I need to replace just the right cat or both catalytic converters.

Related fault codes
P0420
Comments (5)
Anonymous 2014-04-05 09:21

phoenixicez wrote: My 2001 Hyundai Santa Fe AWD with a 2.7L V-6 engine has triggered a P0420 code, indicating reduced catalytic converter efficiency. This model has three cats, and a faulty O2 sensor can cause the converter to fail. I don't experience any drivability issues. Which O2 sensor should I replace? Do you have an OBD2 scanner capable of reading live data from the O2 sensors? This helps determine if the sensor is functioning properly or simply providing inaccurate readings.

Anonymous 2014-04-05 12:09

No fault codes are present for any of the O2 sensors. Given this, can I safely replace just the right catalytic converter, or do I need to replace both converters as a precaution?

Anonymous 2014-04-05 13:38

A dedicated OBD2 scanner that provides real-time live data from the O2 sensors is essential—this allows you to verify sensor performance and avoid unnecessary part replacements.

Anonymous 2014-04-05 18:52

phoenixicez, if you follow kev2's advice and expand your live data monitoring to include additional parameters like engine temperature, load, and exhaust gas oxygen levels, it will provide a more comprehensive picture for diagnosing future issues.

Anonymous 2014-04-07 13:52

Thanks for the helpful insights. I'll review the Freeze Frame data from the scan to better understand the conditions when the P0420 code was set and assess whether sensor or converter failure is likely.