Help please!! 01 QX4 electrical problem

[tomR]

I changed out the right rear O2 sensor and now my 2001 QX4 wont start. When I hit the starter it doesnt engage and instead I get some buzzing noise, intermittent dashboard lights and then the dashboard lights just fade out. Battery is 12.4 volts.

So I double check and make sure I installed the right sensor and I did. I checked all the connections and they are ok. So I put the old sensor on and the same thing happens. What the heck is going on here?

I'm totally at a loss and cant start my car. Can anyone help??Thanks,Tom

[NJ 666]

sounds like a dead battery. What's the voltage when you try to crank it?

[tomR]

You are "Da Man." You nailed it. It was a bad battery. Who would have thought it would go bad while I was replacing the o2 sensor? I dont get it. The battery was bad but the car did crank up (barely) after sitting overnight. Bought a new battery -all is well.

Thanks