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O2 senser, 2001 pontiac montana

Hey, my first time here, I have a 2001 Pontiac Montana van, when i drive i feel like there is just not enough power there. Most of the time when i hit 30mph the engine drops in power, hard to explain so I will try my best. I get in turn the key starts right up with out any hesitation what’s so ever! I leave for work, while driving when I come to a stop sign and stop and take off its gets sluggish so while my speedometer is going up my movement is not changing as it should so needless to say I have to do 80 85 mph just to keep up with the average moving can at 70mph. Once in a while I will give it some gas and let go of it and it would back fire a little not sure why. Resently I had new head gaskets put on cause temperature was not staying where it was suppose to be, they smooth out the headers and did a tune up, not sure about the timing, New fluids, once in awhile the temp would climb but that cause of the fans. Took it to AutoZone they did a obd code check came back with O2 senser and nothing else, so if I replace this will it bring my van back to normal running operation? And would it be anything I could check to rule out?

Vehicle Speed Sensor controls the speedo and inputs to the ecm. Upstream or down stream O2 sensor?

Sluggish engine and overheating could also be caused by plugged catalytic converter.

Cat can cause o2 fails.

My first thought was you may have some kind of slippage in the transmission going on. Making that call with any certainty would depend on knowing how the speed is determined in your car’s design. My second though was coolant getting into the cylinders, but it sounds like you already had that problem and got it fixed with the new head gasket.

I doubt replacing the O2 sensor will be of much help. It’s possible of course. But usually O2 codes are for problems that cause the O2 sensor reading to be off, not the O2 sensor itself. Air leaks or fuel pressure problems are the usual culprits. The only practical way to rule out a bad O2 sensor is to replace it and see though. If a new one doesn’t cost too much, no harm in giving it a go.

A pro-mechanic would look in the vehicle’s factory service data for the diagnostic procedure for that particular code, and go through those steps one by one. Difficult for a DIY’er as often special tools/jigs/test equipment is required.

Blocked cat will reduce power.

Thank you everyone, i will look into that and let you all know how it went