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Discussion Starter · #1 ·
Will an O2 sensor still work in a degraded mode if it is going bad without sending a bad O2 sensor code to the computer? I'm still trying to figure out what is causing my daily driver to show a code for 'lean' in both banks.
 

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I would look for a vacuum line leak first and then if you cant find one I would look for an intake leak. Old timers used to spray carb cleaner around the intake and listen and watch for a change in RPM.
 

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Charles
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rangerdoc said:
Will an O2 sensor still work in a degraded mode if it is going bad without sending a bad O2 sensor code to the computer? I'm still trying to figure out what is causing my daily driver to show a code for 'lean' in both banks.
Based on what mine did I will say it can. My car just didn't seem to run as well as it once did even after changing plugs and other various maintenance work (125k). While having the transmission out three times for TOB problems (another story for another time) I started getting a CEL. It was for a lean condition in one of the banks. I took it to the shop and had both O2 sensors changed since they were old. What a difference that made. The car had not run so well in a long time but it never threw a code until just before I had them replaced.

What code are you getting. I had P1151.
 

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Discussion Starter · #4 ·
I'll be [email protected]! I sprayed some carb cleaner around and found a spot that reacted (I should have tried this before). Under the upper radiator hose (this is on an 02 Explorer 4.0) where it loops over the engine a bit there is a little 90 degree rubber hose that links two rigid vacuum lines. The heat from the radiator hose had melted a hole in the elbow fitting. I never would have seen it (obviously, it's been nearly two months now). I purchased a quick replacement and disconnected the battery to reset the CEL. Tomorrow we'll see if the CEL comes back on. If it does I'll try the O2 sensor as I've replaced nearly everything related to a tune-up as possible.
 

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Check and see if you have a vacuum and/or leak somewhere; like a cracked rubber vacuum hose or something. At least this can get you started.

From my experience with my 2002 Ranger, the O2 sensor can cause noticeable problems before the light actually comes on.
 

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Discussion Starter · #6 ·
So far so good. No CEL today! Though it is still pinging under acceleration (which is why I did all the tune-up stuff in the first place). I wonder if I should go ahead and change the O2 sensor since the vehicle has 109K on it. I'd like to get rid of the pinging before I sell it.
 

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Discussion Starter · #7 ·
Before I waste my money this weekend on a new sensor, can someone tell me if pinging could be caused by a bad O2 sensor? I'm just not sure what else it could be since I did everything else tune-up related. Maybe the timing is a tad off. How do you adjust the timing on new vehicles without hooking it up to a computer?
 

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my 92 f-150 had bad pinging probems...turned out to be a clogged catalytic converter...I also had the code switching rich lean and I put in new O2 sensors and that fixed that problem..I also had a problem of the truck stalling with the defroster on full on when stopped at a light.the alternator gauge would drop...new O2 sensor fixed that problem too...
 
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