Does anyone know the location of the plug for the upstream (in front of the Catalytic Converter) O2 sensor on the Scion xA? My Check Engine Light came on a few weeks ago and I suspect it is the upstream O2 sensor (because my gas mileage abruptly dropped from about 28 mpg in everyday use to less than 20 mpg). I know the downstream O2 sensor is located under the center console (which seems like a lousy place as it requires lifting up that console which isn't that easy if you have the optional arm rest). I'm hoping the upstream O2 sensor has an easier to access plug location. I know where the sensors themselves are located, and they look easy to access. I need to decide whether to do this repair myself or whether to take it to a repair place. If the plug is in an easy to access location, it appears to be a pretty easy job (which would save me a few hundred dollars). If no one knows, I'll get under the car and try to find where it routes to, but if someone knows, I'd appreciate the information.

 

Most I-4 Engines are similar. According to the 2nd video it should be located in the Engine compartment prior to the Catalytic Converter.

Hope this Helps,

MR_LUV

 

Thanks for the information. I used an OBD2 Code Reader, and it turns out the reason the Check Engine Light came on wasn't the O2 Sensor. I also carefully checked my gas mileage on my last tank of gas, and it was 26 mpg, which is about right for my typical driving (mostly city).

The code was P2401. The code reader said Evaporative Emission System Leak Detection Pump Control Circuit Low. I assume that description came from the code reader and the car just output P2401. I'll have to try to figure out what this is.

But if my O2 sensor does go bad in the future, at least I will know where to look.