I have no cel on my 99 obw 2.5 but the mileage kinds sucks ( ave 18 to 20 mph) new plugs wires, filters, etc. Want to check the front 02 sensor to see if its original. I'll just change it if its original. Any way to tell? 140k

I recently changed the front 02 sensor on m 99 OBW. The old sensor set off a CEL, and the code told me the sensor was bad. This was at 190 K miles on my OBW. I am pretty sure mine was the original, but who knows for sure when you buy your car used.

 

I am guessing you bought yours used, and so don't know the early history on the car. I don't think there is any reliable way to know if your 02 sensor is the original. If it is not throwing a CEL, I wouldn't replace it. You might be better served by adding Seafoam to your gas tank, and also fed directly into your engine to clean out deposits.

 

Adding a good quality fuel injector cleaner would be a good idea too. Just don't add both products to the gas tank at the same time.