2014 R-SPEC O2 sensor problem

[oklawall]

I have had my R-SPEC for just under a year and have now had the lower O2 sensor on the right hand side change for the 2nd time and the lower Left o2 sensor change once and all 3 went bad or code was for too lean. The dealer just wants to replace the sensor and send me down the road.

Right hand #1 was changed out at 8,000 miles, went bad on a trip from South Carolina to Oklahoma about 4 hours of highway driving

Left hand #1 was changed at 26,000 miles, went out on a road trip from Oklahoma to Indiana after about 5 hours of highway driving

Right Hand #2 was changed at 35,000 miles, went out on a road trip from Oklahoma to Indiana after about 2 hours of highway driving

Had grandkids in the car so at the most was only going 10 MPH over the posted limits so between 70 and 80 MPH

Run 100% 91 octane rated gas only

Hyundai dealer has not been able to find what is taking out my O2 sensors they think that it is just bad sensors, but could not produce anything from Hyundai for a recall or a bad batch of O2 sensors so I don't think that is the true problem. Because all of them had been down stream / lower O2 sensors I was thinking maybe the CATS could be the only cause.

Do any of you have any suggestion on what would cause the downstream/lower O2 sensor on both banks to go bad and not mess with the upper O2 sensors?

 

[427435]

Is there any pattern to your gas buying??

That is, does the O2 sensor go out after buying gas from a different station than normal?

 

[oklawall]

Is there any pattern to your gas buying??

That is, does the O2 sensor go out after buying gas from a different station than normal?

The first 2 O2 sensors yes but the 3rd was running on the gas from the station I always go to

 

[mikec]

I'm assuming the Genesis uses modern "wide band" O2 sensors - a lot fancier than the original O2 sensors used back in the 1980s... these sensors can determine the actual rich-lean ratio in the exhaust gasses; the original sensors could only determine "rich" or "lean" but not "how rich" or "how lean." Today's sensors (which came about because of OBD-II requirements and eeking every last bit of MPG from engines) are far more capable, more expensive, and more fragile. They also require a "controller" module - typically part of the ECU in modern cars. One requirement of many modern wide-band sensors is that the sensor power, controller, and heater be functioning BEFORE the sensor is exposed to exhaust gasses... otherwise the sensor will be damaged and/or its calibration will be contaminated.

Thus, flaky wiring to/from the ECU/controller to the sensors could be a contributor, as could issues internal to the ECU. For example, whatever the ECU uses as a power source for the O2 sensors & controller could be intermittent... leading to O2 sensors being exposed to exhaust gasses while the controller is offline...

The O2 sensors downstream of the catalytic converters are there primarily to monitor the performance of the cats - another OBD-II requirement. Bad cat converters will generate readings outside the expected range... and the ECU could be flagging that as O2 sensor failures. Leaks in the exhaust pipes will also screw up the exhaust gasses leading to incorrect O2 sensor readings. Have your dealer carefully examine the cat converters, the exhaust pipes especially at the joints, and the wiring to/from the O2 sensors all the way to the ECU. I can't think of a good way to test the ECU as your bug is probably intermittent... and they won't want to swap in a known good ECU for testing - throwing expensive parts at problems is not going to be Hyundai's first choice.

mike c.