Question

PO430 on 2007 Nissan Xterra. Should I "start" by replacing O2 sensor 2 (rear sensor), or O2 sensor 1, (front sensor) , or even "both", before I replace a more expensive Cat? Thx!

Answer 1

Instead of replacing the sensor, you could try using high octane gas for a couple of weeks, and if possible add a fuel additive, sometimes that will work too. If the code comes back, I wouldn't suggest replacing the sensor, usually the problem is that cat.