I had this P0174 thing going on. and then the other side would eventually be flagged as well. I checked a lot of things based on info from this forum, vacuum leaks, pcv stuff, elbow in the back, nothing really stuck out as a problem, not even spraying flammable liquids looking for vacuum leaks. I wasted a lot of time trying to track it down and just finally said screw it I'll change all the intake gaskets and rubber hoses that I could find.

Well while going through that process, I happen to find that my drivers exhaust manifold was cracked under the runner toward the firewall. I put off changing it all summer because it looked really nasty with all the rust and the nuts looking like there was nothing to grab onto and besides the truck ran great... no hesitation... gas mileage didn't change. I had the parts in hand just really wasn't enthused about taking on the project, based on it's appearance and clearances (plus I'm too cheap to pay a mechanics part prices when I can find the parts for half the price). Well I finally got around to changing it just yesterday and the process concluded without one hitch.

So I thought I'd clear the codes and if by chance the same ones come back I'd take the plunge and change the intake gaskets (already have those parts too). Cleared the codes and took it for a drive and now I have two new codes <slaps forehead> P0155 & P1151 I didn't really get to drive it long enough for the original codes to show up yet, so they still may surface. One 14 min drive to the parents, and another 2 min down to the gas station and 2 min back to parents. So I'm looking at my code reader/logger. And I see the o2 sensor is showing 0 volts output all the time. Since the advice on this forum is varied regarding P1151... Is it safe to assume (I know.. that's never safe) that the sensor is dead or a wire is broken, or do I still need to be looking of vacuum leaks and EGR issues? I'm gettin sick of looking at that darn check engine light when the truck runs perfectly fine.

 

P0155 Heated O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 1)

P1151 Lack Of HO2S21 Switch - Sensor Indicates Lean

1151 is Bank 2 Sensor 1 as well.

You nicked the wire, got it wet or didn't plug it in. Drivers side.

I doubt it went out, but it's possible when rebooting after works done. Check the wiring/ clean and inspect the connector. Special attention at the top of the sensor, the wires tend to chafe or loose insulation there. These wires are sensitive.

Good Luck

 

turns out the connector had almost completely fallen out, apparently just a coincedence. Heater circuit is still not working though (hovers at .9 volts on warm up), but I can live with that. The sensor came to life after the temp needle hit the normal range on the dash. Now we wait to see if my P0174 code comes back. thanks jbrew