Rep Power: 0

2008 Honda Civic Hybrid. Just bought it the other day. Has p0420 and p0171. For the p0420, I scanned the o2 sensors and sensor 1 is getting 0 volts and sensor 2 is fluctuating a lot. Could sensor 2 fluctuate a lot because of lack of readings in sensor 1? Or simply just a bad cat?

any experience with the cheaper aftermarket cats that are like $200?

car has 266k on it and otherwise runs really good.

thanks all

 
Rep Power: 222

Cheap cat might last a year might last 6 months.
if you're going to buy o2s but the correct denso ones.

 
Rep Power: 0

Is it worth buying both new o2's or going directly to a new cat? I was going to check the fuse for the upstream sensor and make sure it wasn't unplugged or broken wires first.

 
Rep Power: 222

Old o2s might not come out of the old cat. Plus they will be reading alot slower compared to new ones.