I have a 2009 Hyundai Accent 1.6L. When the engine is idling, at full operating temperature, the upstream sensor voltage reads .195 to .795. However the downstream sensor voltage stays steady at .795 volts. Do you think that the downstream sensor might be bad?
O2 sensor voltage output question
- Thread starter neilwestlawn
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Yup. Slow switching means the Cat is good.
It may read differently in the cold start "open loop" mode but with a good cat it will stay steady after warm up unless you go to WOT where many cars go open loop again.
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It does cycle and then becomes steady. I was concerned about the number being so high at .795. I thought it would be more like .46
Originally Posted By: neilwestlawn
I have a 2009 Hyundai Accent 1.6L. When the engine is idling, at full operating temperature, the upstream sensor voltage reads .195 to .795. However the downstream sensor voltage stays steady at .795 volts. Do you think that the downstream sensor might be bad?
Over the years I have read that 350-650mV is normal, others claimed 750mv show the cat is operating most efficiently.
In practice anything in the 300-900mV range seems to be fine as long as its steady and not switching quickly. Once the rear O2 starts to mimic the front the cat has lost its effectiveness.
I have a 2009 Hyundai Accent 1.6L. When the engine is idling, at full operating temperature, the upstream sensor voltage reads .195 to .795. However the downstream sensor voltage stays steady at .795 volts. Do you think that the downstream sensor might be bad?
Over the years I have read that 350-650mV is normal, others claimed 750mv show the cat is operating most efficiently.
In practice anything in the 300-900mV range seems to be fine as long as its steady and not switching quickly. Once the rear O2 starts to mimic the front the cat has lost its effectiveness.
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