my dad is having trouble with the Focus. it doesnt start. he first thought the fuel pump or filter or along the lines of gas not reaching the engine. but those are fine and gas reaches the fuel rail. there is spark. he borrowed a scanner and it pointed to an O2 sensor which was replaced. but its still the same. what else to check?

The O2 sensor was replaced but the code is still being thrown?

Was the battery disconnected for the install? If not disconnect it step on the brake pedal. Wait 20 minutes then reconnect. Pray that during the install the electrical did not arc across the computer.

sensor was swapped out with battery still in. code cleared and tried to start it. but still no go. any scan since then is incomplete. and how long of a brake step?

couple seconds to discharge any residual electrical charge.

problem found. store tomorrow.

What was the problem?

timing was off due to the broken tension pulley.