if the car (2006 XJ8L 4.2) was running lean enough to set off the 02 sensor, would you feel it?? like a shaky idle or hesitate to accelerate? i kept getting a lean code in bank 1 #2 sensor, and put fuel injection cleaner in the tank twice and ran it a hundred or so miles at speed and the light has not come back on, but it never ran bad.. after clearing the code before the cleaner, just after a day or so the light would come back on.. after the cleaner so far it has been off for almost a week now.. still holding my breath..

 

You might feel it but usually don't.

I'd watch the fuel trims. If you've an air leak you'll damage the cat(s) if you leave it.

 

well so far, no light. and all i did was put another strong injector cleaner in the tank and run it a 200 miles. if there was an air leak, that would have triggered the light by now. i think i had a semi clogged injector on that bank that was leaning out, and putting in the cleaner back to back got it working again.. That is my hope at this point. it has always come on way before now.. Thank you for your help.

 

Which brand injector cleaner did you use?

 

I'd watch the trims. They have to be way out before a code but want attention if they are somewhat out - and can be doing slow cat damage if they are like that.

 

how do you check them?? i guess my mechanic would know.. Thank you.. as i said the light has NOT come back on and it always came on pretty fast before, i think it was dirt in the injectors on that side or just sticking, because since i used the cleaner, the light has stayed off..

 

i think it was call Sinclair injection cleaner, i have used it before and it really works!!!

 

Any OBD tool with live data.

Elm327 is cheap and good.

 

the car is a 2006 XJ8L with 4.2 Liter V8 with 155K on it

where would the air leak be most likely?? the intake? fuel rail o rings or bad injector o rings??? the light stayed off for 2 weeks and after a long run and then sitting for a couple hours it came back on again plus fuel mileage was down on the return trip... This is nuts, plus it has already cost me a ton for parts and it still goes on.. i am running out of money to throw at this.. i love the car, but i may have to sell it.

 

Watch live data. Spray tiny amounts burnable gas.

 

let me guess po171 and po174?

 

A vacuum leak may not be sufficient to set a code while driving at highway speeds but will upset things while sitting in traffic or idling.

Stop throwing hokey fuel injector cleaners or other additives at the car.