Originally Posted by bmylez
An O2 sensor will reach operating temp just a little later than if it were mounted in the downpipe, mainly because it's a turbo car. If he does 10 sec of boosting, the sensor will be plenty hot.
O2 sensors heat themselves thats not the issue. Its the delay in reading, if its for a wideband it will be off 200-300 Rpm. I use gas analyzers and on average at the end of the tailpipe it takes about 3-5sec for the gases to travel there.