I’m going to break two of my normal tool tendencies with this one. This is a crow’s foot (which I normally think is a pretty pointless invention), and it’s from Harbor Freight (who I have trouble trusting). But I make these exceptions because this tool, especially at Harbor Freight’s admittedly excellent prices, will save you a contortionist’s act whenever you need to install or remove an oxygen (air-fuel ratio) sensor.
Manufacturers seem to compete amongst themselves to place these in the least convenient places possible, with the wiring arranged so that removal is nigh-on guaranteed to twist or crush the conductors to breaking. Some types of O2 sensor sockets are just deep-wells with a slot, and will (repeat WILL) torque the wires right in two.
The crow’s foot version sidesteps that problem neatly and pairs well with a flex-head socket, since manufacturers like to place their sensors on top of the exhaust pipes, forcing you to reach up top where rigid wrenches and ratchets can’t get. This $4 Harbor Freight crow’s foot will settle their hash. There’s another version made by Performance Tool and retailed by Northern Tool available for a little extra ($7.50) if Harbor Freight makes you nervous.