17521 - Oxygen (Lambda) Sensor: B1 S1: Internal Resistance too High
 

Can someone please confirm which Oxygen Sensor this is supposed to be:

17521 - Oxygen (Lambda) Sensor: B1 S1: Internal Resistance too High

The check engine light that was triggered by this code has gone away not however...

Are there any other problems that could cause this code to be logged?

I have noticed my mileage is a little worse than it was half a year ago and apparently bad ox sensors can cause this, no???

Passenger front, which is the easy one to replace.

Awesome thanks.

I'm not sure what it is in the o2 sensor that causes this code but it typically means that the sensor is failing. If it was totally Kaput you'd have a "short to ground" code. Yes, a bad O2 sensor can decrease your fuel efficiency.