Question oxygen sensor 2000 4runner

[HuntHead]

Having trouble no power, backfiring, stalling, rough idle. Have changed oxygen sensor between manifold and catalytic converter. As we were getting a 171, 172 on the code reader. Still having same code readings/trouble. How tough to change other O2 sensor between catalytic convertor and exhaust? Any other thoughts on this problem?

Thanks in advance for all your responses and assistance. Greatly appreciated.

[JRE56]

Originally Posted by HuntHead

Having trouble no power, backfiring, stalling, rough idle. Have changed oxygen sensor between manifold and catalytic converter. As we were getting a 171, 172 on the code reader. Still having same code readings/trouble. How tough to change other O2 sensor between catalytic convertor and exhaust? Any other thoughts on this problem?

Thanks in advance for all your responses and assistance. Greatly appreciated.

Take a look at your MAF sensor it may need cleaning.

[RobXS]

P0171 is too lean and P0172 is too rich. Odd that you would get both because they are opposites. I would look under the hood before replacing sensors. If it is running that bad then that is probably something more than a bad 02 sensor. As already stated, clean the MAF sensor. I would probably replace it. You should also check your fuel pressure and fuel pump. Also check for vacuum leaks.

[HuntHead]

Thanks for the reply's I will try to look at this vehicle this week. With summer and all it may take me longer to get'r done. Have a nice day.

[larsdennert]

There are two sensors, One is a fast reaction and one is slow. Both are expensive and there are specific codes for them when they fail and give readings out from normal or stop cycling. Keep hunting.