Oxygen sensor's kaput
 

my service engine light came on and i checked it out. turns out it's a PO 420 (Efficiency below threshold). i'm guessing it's for the oxygen sensor. is that right? also, what's the purpose of it besides sensing oxygen?

P0420 is Right Bank 3way catalyst malfunction. Have you done any mods to your car recently? If not then it's probably just the ECU needs an update. Some 2000's had parameters for the cats programmed too tight and gave false errors. This might be happening to you. Real O2 sensor failures have been rare so far in the 5th gens.

BTW, O2 sensors read the amount of free oxygen in the exhaust stream. The ECU reads this signal and determines whether you're running lean or rich.

http://www.nhtsa.dot.gov/TSBScans/sb619999.pdf

hey, thanks sly. i haven't done any mods so u're prolly right. i thought it was that pesky oil change timer, so i disconnected the battery to reset it. then the light came back on.

man...that's a long bulletin. guess i'll print it at work...

I have that problem with my 2k Fed emission, any update on this?

thx

hey sly...u're right. i got it fixed with that bulletin. thanks again!