Thank you for your vote.
Ask your mechanic exactly what code is being stored. There are multiple codes that have to do with an oxygen sensor. There is a code that says the oxygen sensor reads a lean condition, in which case the oxygen sensor is NOT bad, merely being a messenger of another problem. There is an oxygen sensor code reading "too rich". Others for "out of range too low" or "too high" and anything in between. They all point to different problems and if we can know the exact code that would give us trail to follow. About the only codes that indicate that the sensor may be bad are ones that say it is responding too slowly and isn't even showing up on the profile.
If it is a vacuum leak, then the code that would MOST LIKELY show up is a code from the oxygen sensor saying you have a lean fuel mixture condition. That is because a vacuum leak is unmetered air being drawn into the intake that the computer doesn't know about. Causes bad driveability problems.
You saying that the car bucks most often going up a hill with a low tank of gas is a tough one. The only two things I can think of is that the tank has some water or sludge in it and when the tank gets low the pump will pick that stuff up. Other thing, the tank is vacuum sealed. Your gas cap should hiss when you remove it to fuel up. If it doesn't, then the cap might be bad.
I hope this helps. Again, let us know.
Thursday, July 19th, 2007 AT 10:22 PM