all 4 O2 sensor heaters throwing codes

The CEL in my Jeep has been on for a while, I knew that the downstream sensors needed to be replaced from checking the codes a couple months ago. Finally got around to replacing them with Bosch sensors a couple days ago. Now that I've done 2 or 3 trips with it, the CEL is back on. Checked the codes and it's showing P0135 P0141 P0155 P0161 which relate to all 4 of them complaining about the heater.

Any ideas where to check? The upstream sensors were both replaced with Bosch sensors last summer, approx 5000 miles ago. No codes back then.

o2 heater fuse intact?

check for blown fuses and short circuits in the wires

Interesting, fuse 17 in the box under the hood is blown. I'll replace it and see what happens then. Could a bad O2 sensor short itself out and blow the fuse?

Sure could. Probably got taken out by your old sensors.

Replaced it last night and made a couple trips, no CEL or pending codes. Thanks for the help, I was going to search for wiring issues first.