Throwing codes one after another!! Holy...

dodgeneonzl · Post by **dodgeneonzl** » Mon Dec 05, 2011 10:47 pm

So it all started with P0420, so i figured i might as well change the downstream O2 sensor and maybe that would fix the problem. So after changing the downstream O2 sensor for a day, P0128, and P0138 popped up. Okay, P0128 was the thermostat, replaced and check. So now I'm still left with P0138 which is （P0138 HO2S Circuit High Voltage Bank 1 Sensor 2）so it seems like it's the downstream O2 sensor...

Since i just replaced it, do you think that my cat is really shot? Or should i replace my upstream O2 sensor? Both upstream and downstream were still the original sensor (except now i already changed the downstream).

Post by **occasional demons** » Mon Dec 05, 2011 10:59 pm

See reply in the t,stat thread.

Edit for search purposes:

occasional demons wrote:
I would give it a day or so. Possibly with it running cooler than normal, it may have been running a bit rich.

dodgeneonzl · Post by **dodgeneonzl** » Tue Dec 06, 2011 12:38 pm

aye aye Captain!

dodgeneonzl · Post by **dodgeneonzl** » Sun Dec 11, 2011 6:22 pm

So, just like occasional said the engine light did go away after 2 days but when i do the key dance it still shows P0138... and if i put the key in and turn it to on position without cranking it, the check engine light will start to flash. I believe the check engine light just stay on before, but now it'll flash. Anyone know what the deal is?

I think i heard someone said to change both up and downstream O2 sensors together otherwise it will throw a code?? Could this be it???