Las Vegas Area
Join Date: Jun 2006
Location: Las Vegas
SC6311 is offline
Re: signs of a bad o2 sensor
To be honest, I don't think it would be your O2 sensor. Reason being is that our trucks(not having a MAF sensor or even knock sensors) are designed to run in open loop all the time. The O2 sensors are there simply for emissions..as in the computer is looking for a difference between the front and the rear one. If it sees that the resistence and difference between the pre and post cat are where they should be, that means that the cat and the O2 are working, so you dont get a code. If there is an issue with one or it sees the exhaust stream to be identical(as in the cat is ineffective) it will throw a code.
On many cars, having a bad front O2 will cause it to default to open loop even when cruising..not exactly the best mileage. On our trucks, what is written in the tables is what it is. (based on load and MAP and IAT sensor volatge)
You may want to check the IAC and make sure it is doing its job. The coil packs/wires/plugs would be a possiblity as well. If you have never replaced your fuel filter, it wouldnt be the worst time either..they are typically neglected as much as anything.
2000 S-10 in Pewter Metallic 2WD (K&N FIPK, shaved badges, tint, billet bowtie, Low-pro tonneau, Gibson cat-back, Sensa-Tracs, Rockford/Alpine system and Dynojet WBC2)
a 2003 Pontiac Grand Am SC/T Coupe(my baby)