Replaced O2 sensor and the code did not come back on. Somehow the O2 wire got pinched it appears and made it go bad. Wish would have known this was issue as replaced the entire O2 sensor. Good reason to inspect wiring thoroughly before replacing and do check with multimeter.
Removed battery power overnight made no difference. Cleared codes several times with scan tool codes come back within 5-10 secs of being cleared.
I wondered that but didn't find any damaged or broken wires. Continuity on downstream O2 sensor is good, downstream only one I unplugged yet the...
I did not have these codes until I removed the exhaust on passenger side to repair heat shield. The downstream O2 sensor was unplugged due to this.
270K on truck 4.0 L V6 and mpg has dropped dramatically after 100 miles only half a tank around town going 50 miles burns quarter of a tank...
Getting really bad gas mileage.
I unplugged one O2 sensor and then started getting P0031, P0100, and P3100. Have cleared with scan tool and codes come back immediately.
One interesting thing is when unplug MAF sensor let it stall then start engine again there is no O2 sensor heater circuit...