Oxygen sensor

[06YarisRS]

Originally Posted by Spellino

Hello Yaris world. So I took my 2007 sedan to the Toyota workshop. After diagnosis, it came out that my check engine light is on because the oxygen sensor isn't working anymore.

What does it do? Can I buy one from AliExpress to DIY?

Did they indicate if it was the upstream (wideband) sensor, or the downstream (post-cat) sensor? The upstream sensor measures air/fuel ratio, the downstream sensor measures residual oxygen after the exhaust has passed through the cataylic converter. Upstream sensor = more expensive, can affect driveability, fuel economy, downstream sensor = less expensive, should have no effect on driveability. It is an easy DIY job but finicky. The hardest part I found was getting up into the car and unclipping the connectors. I bought a very cheap (~$17.00) downstream sensor, but wouldn't have cheaped out on the upstream if I had had to replace it.