Girlfriend was driving her 2000 GMC Jimmy home the other day and her engine light came on and she smelt something burning and it stunk bad.

When i got home i scanned the codes at it was. P0147 - O2 Sensor Heater Circuit Malfunction ( Bank 1 Sensor 3)

Now i ripped the truck up and down the road and runs fine no smell. cleared the code and truck seems to be ok never came on again. I would just think it was random but the smell at the same time concerns me. I dont want her getting stuck somewhere.

I have suspected the CAT was dieing and if u hit it u can hear parts moving around. My thought is that it got clogged for a moment and sensor went lean and the truck chocked on its exhaust. Sound possible?

I would Appreciate any input. Thanx