Sequoia Oxygen Sensor Issue

I've encountered similar symptoms in my Sequoia. If the error memory stored a fault related to the air-fuel ratio or specifically mentioned an O2 sensor, then it is very likely you're dealing with an aged oxygen sensor. Before replacing it, I would recommend checking the wiring harness and connectors associated with the sensor. Where is the error exactly, pre-cat or post-cat?

The error refers to the upstream O2 sensor, before the catalytic converter. What exactly did you do to fix the issue on your car?

In my case, the symptoms were quite similar to yours. Initially, I tried cleaning the connectors with electrical contact cleaner, but the problem persisted. Eventually, I took it to a trusted workshop, and they confirmed that the sensor was indeed faulty. Considering the age of our vehicles and the mileage, it might be time to consider a replacement rather than further troubleshooting.

I took your suggestion and visited my local mechanic. It turned out to be a faulty O2 sensor, just like you said. They replaced it for 95€. Now, the error is gone, and the fuel consumption seems normal again.