So it goes closed at 140. It will run fine for about 15-20 minutes. Then it will randomly go open loop again at normal operating temps. I just had the SES light come on with the following codes

P0150
P0174
P1174

any ideas where to start?

 

I searched the codes and found a lot of people with similar posts, but I can't seem to find a solution anywhere. If I hadn't washed the engine, I would probably be inclined to replace the O2s, but I didn't have any problems until I did that...

 

With your mileage and 1 dead front 02, I would replace both the fronts then clear the codes, that should fix it.

 

Thanks mike. I read a couple of other posts where they replaced both sensors and then the codes came right back after a month or so... Is there any thing else I can check before I replace them?