Goldenpony

OK, I have a 2006 GT, 4.6L with a little over 170K miles on it. I have never changed the O2 sensors. The engine runs well, mileage is reasonable. Should I break down and install new ones? How many are there? What kind of improvement can I expect if I install new ones?
Thanks in advance.

Dino Dino Bambino

If you aren't getting any O2 sensor fault codes, you can leave them alone.

Goldenpony

Thanks Dino, I decided with a ton of miles on her, I am going to change them-even with no CEL.

Dino Dino Bambino

In that case keep the old ones as spares since they're still good.

danzcool

Should be 4 of them, pre-cat and post-cat on each side.

Goldenpony

OK, has anybody changed the driver's side upstream O2 sensor? I changed the other 3 but don't see how to change the last one. I may take it to a shop and pay to have the last one done unless someone can tell me some "trick" to do the driver's side upstream sensor.

imp

I have a much earlier car, 1994, but found the driver's side front O2 was easily accessed via under the wheel-well. If necessary, use a crow's foot wrench.

Goldenpony

Thanks imp. I will give that a try.

Dino Dino Bambino

The driver's side upstream O2 sensor is in the exhaust manifold. You might just be able to see it from inside the engine bay but it's difficult to reach.

Goldenpony

Thanks Dino, I can see it. I might try what imp suggested-if that doesn't work a shop I trust said they'd install it for $70.