Need Mechanic's Advice

[Kate Andreozzi]

Helping out my sister who had a check engine light on. She has a Hyundai Elantra. Went to Autozone and had the code come up as P0139: H02S12 circuit condition (heated oxygen sensor bank sensor 2). Probable cause was oxygen sensor defective, fuel system running rich or lean, engine misfire, or fuel pressure very high or low.

Is there anything I can do before bringing it to a mechanic? I was thinking of cleaning the O2 sensor first and go from there. Any suggestions or advice? The engine is running fine, car drives with no symptoms. Thank you in advance.

 

[Richard L]

Kate, I don't think there is much point in trying to clean the O2 Sensor. If you are mechanically inclined, and you have the tools, it's not too hard to replace the bad sensor. The fact that you asked this question makes be believe you don't feel confident changing the O2 senor yourself.



My suggestion is to got to several shops and get quotes of what it would cost. Many will not give you a cost until they run their diagnostics and typically want to charge you about $100, but most will deduct the diagnostic charge from the labor cost if you choose to have them do the repairs>



...Rich

 

[Yardsale]

You could replace the oxygen sensor.



Ya; I'd just replace. One can attempt to clean an oxygen sensors, but I doubt it will fix the problem.



What year how many miles?

The car seems to run fine?



Bank 1, sensor 2 (after the cat).



<a href="http://www.obd-codes.com/p0139" target="_blank">P0139 OBD-II Trouble Code</a>



<a href="http://www.youtube.com/watch?v=BPkuBtDIPzE" target="_blank">How To Replace Install Downstream Oxygen O2 Sensor 2001-06 Hyundai Elantra 2.0L</a>

 

[Mark Price 2]

Easiest thing to do first is to visually check wiring for corrosion or frayed wiring. Common for O2 sensor wires to rub threw the insulation and short to the frame. Also common, if it has been replaced before, that the "spliced in" wiring on a aftermarket sensor has corroded or rubbed through(or poor work).

Listen for an exhaust leak as well while your under there. Around the flex pipe. Very common for that pipe to get damaged. My wife used to hit it on boulders or something all the time in our old honda.

Be safe. Jack and jack stands required!!!!!!!!!!

Cross your fingers way: replace it yourself and hope that was the issue.

Best way: diagnose with a scan tool that reads live data.