I had a bad o2 sensor code and looked at the fuse and yep, it was blown. So I replaced it, drove it around the block to see how fast it would blow and nothing. I also checked the wire loom and all and nothing burnt, chafed etc.

So what could cause it to blow if there is no obvious issue and no immediate blowing of the fuse?

 

Follow the wiring from the sensor and look for spots that may have been melted to the exhaust manifold.

 

the heating element inside the o2 sensor can make a short.
anyway, i would allways replace an o2 sensor if there is the smallest issue. it has a big impact on fuel economy and how the engine runs.

good luck

 

Ok I'll see if it comes back. Like I said I did check the wiring as far as I can see/feel/check.

If it blows again, I'll replace it. I have to take it to the emission place soon ( 60 days or so from now ) so I'll wait get an extension and take it back to show I've been trying to fix it. Hopefully after X amount of dollars, they will make an exception for it.

Ive heard of them doing that before...

I dont see how they expect a car with 211,000 to run perfect or stay within specs...

 

As mentioned, the sensor itself is a primary suspect if wiring checks out.

I search for NTK brand sensors when replacing (an OEM supplier to Jeep).