Where is the oxygen sensor located?

Hello,

You selected the vehicle to be a 1997 C-Max. Ford made the C-Max from 2003-2019.

Can you verify the year of the vehicle?

There are a number of reasons for black smoke coming out of the tailpipe, including bad oxygen sensor.

It could be due to a shorted fuel injector, bad fuel pressure regulator, vacuum leak, stuck open EGR valve etc.

Here is a helpful guide:

https://www.2carpros.com/articles/engine-black-smoke

On a typical 4-cylinder engine there are two oxygen sensors. One is on the exhaust manifold and the second one is after the catalytic converter in the exhaust pipe.

Are you getting oxygen sensor codes?

Please let me know the year of your C-Max and I will see if I can provide you with a diagram.
Thank you.

The vehicle is a 1997 Ford CWS Econoline V10 Van.

I was told it might be the oxygen sensor. I took the van to the Ford agency they had the van there for 3 days and could not find the problem. This one guy said it could be the oxygen sensor. But I cannot locate it. That's why I'm asking if you can tell me where it is located. If possible, can you send an image?

This V10 should have three oxygen sensors. See diagram below for the location.

The best course of action would be to take a look at the guide and go through the possibilities to find the issue. This way you are not replacing a part that does not need to be replaced.

Are you getting any codes? Is the check engine light on?
If so, scanning for codes can help with the diagnostics.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing