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Randall C
Randall C, ASE Master Tech
Category: Hyundai
Satisfied Customers: 12803
Experience:  ASE Master Tech, L1 diagnostics, 32 years. Electrical expert
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2006 Hyundai Elantra: sensor circuit..the O2 sensor..volts

Customer Question

I am working on a 2006 Hyundai Elantra and I have a P0139 code, O2 sensor circuit slow response bank 1 sensor 2. Viewing the data I see the slow response response from the O2 sensor and feel the sensor is failing. My confusion is that bank 1 sensor 1 is reading over 1 volt up to 2 volts and I did not think it would go over 1 volt. It is reading between 1.84 to 2.04. Bank 1 sensor 2 voltage is below 1 volt changing between .1 to .9 but slow. What is wrong with sensor 1 reading and why am I seeing over 1 volt.
Thank you
Submitted: 5 years ago.
Category: Hyundai
Expert:  Randall C replied 5 years ago.
Hello, I am Randall. I will do my best to help answer your question

A bit hard to explain but the bank 1 sensor is a different type sensor. its normal value range is 1.9-2.0 volts with a fixed voltage of 2.0 upon de acceleration. What you are viewing is right perfect for the bank 1 sensor.

the bank 2 sensor reads from 0v -1 v only ,

the value chart for the bank 1 sensor is below.

Most likely as you have suspected, you have a failing bank 2 sensor

Randall C and 2 other Hyundai Specialists are ready to help you
Customer: replied 5 years ago.


Thank you for your answer it helps a lot. One more question do you know if sensor 1 voltage is specific to Hyundai or other car makes e.g. foreign or domestic. Does it vary by make? Do you need shop manual to know? Where else could you find out that info?


Expert:  Randall C replied 5 years ago.
every vehicle, every sensor can be different. I am not saying each and every one is different voltages but yes.. can be vehicle specific. On this one? the front sensor is very different than the back sensor. if I remember correct the front o2 has 6 wires and rear maybe 4-5. most?GM sensors , non heated can be same sensor and readings for all four on a 4 sensor vehicle. it just all depends on what you are working on. yours? front very different and different readings
Customer: replied 5 years ago.
Thank you
Expert:  Randall C replied 5 years ago.
Your more than welcome. Please LMk if you have any followup. Thanks