Sorry to go off topic, but we have a lot of talented mechanics on this forum and hopefully one will be able to answer my question.

On my father's old 1995 Thunderbird, the car has a hesitation and sometimes stalls when cold. The ck engine light comes on frequently. We pulled the code and it is a 181. Unfortunately, the decode is somewhat vague about cylinder bank one being rich, but doesn't say what sensor is bad or if it could be an injector problem. The car runs fine otherwise and doesn't seem to be running rich The cylinder heads were just done by a reputable machine shop, so mechanically the car is fine.

I appreciate any direction you folks can give me.

Thanks, Barry

Are you sure it's a 181?? That is a fuel temp sensor error and I don't think that vehicle is equipped with one. It may be a 171 which is a lean code for bank 1-this most likely is caused by a vacuum leak. It could be there was a hose missed or disturbed when the heads were done, or it might have a manifold gasket that didn't seal well. Also if this is a 4.6, check the big pcv hose at the rear of the manifold, they get squishy and leak after a while-very hard to get at.

Thanks Ted. Yes, it is definitely a 181. This may sound dumb, but it acts much more like a sensor than a vaccum leak. The problem isn't consistent, it's sporadic, it will run perfectly fine then all of a sudden start sputtering. The fuel mileage seems the same too, so I would expect that may suffer if it had a vacuum leak. No high idling condition either.

Thanks, Barry

Whoops, not OBD2- my bad.

181 (M) Fuel system was lean at part throttle Single, Right or Rear HO2S - Fuel control

Looks like if it's intermittent it may be an O2 sensor going bad-assuming no vacuum leaks. You may need to get it on a scanner and watch voltages on the O2 sensors, sounds like one is weak and not happy at part throttle.

Ted - Man, I can't thank you enough, I'm an old classic Corvette / Cigarette guy and don't understand this newfangled stuff. I really appreciate your time.

Barry

No sweat, hope to see you at the races in September.

Is that Cambridge or Ocean City?

both

Obviously, I'm in OC a lot. If you get down this way, let me know and we'll get together for a drink. I will surely be at the OC race, probably not in Cambridge.

And a 95 is not "old". That was just yesterday to some of us. 1955 t-bird would be old.