Both reduced performance and check engine lights are on. Tests show codes 111 intake air temp problem, 171 and 174 both banks lean and the note says lean fuel fault suspect H02S. I have replace all 02 sensors except one down stream. When the others failed the car ran fine but now as long as the reduced performance light is on the car shudders and wont accelerate. When the light goes off it runs fine. I might also add that the 1500 RPM surge until warm up has gotten worse. Any thoughts? Don

 

Clogged catalytic converter? An easy way to tell is after driving, reach under the car see if there's a different in heat coming from the cat (eg driver or passenger)...Don't touch the cat, it could be super hot. If they're both clogged or nearly clogged you wouldn't be able to tell a different but they'll both be extremely hot...

 

I'm guessing those codes mainly start P0 except the 111 doesn't and is - I hope! - P1111. Well worth your time to use the full code and then Search on each and read but first read what the free codes PDF in the FAQs says.

If it is indeed P1111 be sure to realise what it means rather then what you have so far - utterly different.

BTW, you've not said which engine........

 

Turned out to be caused by a crack in a shaped hose conected to the throttle body just past the MAF and throttle position sensors. It is attached to a metal tube which seems to run down under the engine, probably a crank case type vent. I replaced the shaped hose with a regular hose then used hose clamps for a good seal. Started the engine and after about 10 seconds the restricted performance dash light went out. Have not driven the car yet but I am sure that was the main problem Thankss, Don

 

I have driven the car but had to take it to a guy to have the faults and dash check engine liflights removed. All is well Thanks to all. DOnR