Quote:
Originally Posted by bawareca
I am not going to argue with you here. It is your car and your money, but if you go this route you have to change at least the MAF too because he also gets de-calibrated over time and it is also a factor in the short and long fuel trim adaptations. However there are a few very important facts that you are missing:
-The pre-cat sensors in your car are so-called wide-band O2 sensors. You can Google, but in a few words they are sensors with a very precise readings. Compared to the regular O2 sensors of the yesteryear is like comparing Huyndai Pony to BMW M3. The DME will figure out something is out of spec long before you will find some difference in the MPG, let alone a danger to the catalytics.
-Post-cat sensors do absolutely nothing for the fuel economy or to protect the catalytics. They are there to monitor their efficiency.
-All 02 sensors are made for heat. As a matter of fact they dont even work when they are cold.
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If.you look at bmw.service info they advise replacing the O2 sensors at 100k. The exhaust really beats on the fronts so replacing those first is good. Now.they are pricey and one can let it go til failure per my offer message. The maf isn't subject to punishment of exhaust and has no wear service interval.