Is this the Oxygen sensor B2S1? Plus questions related with PO153 | Ford Explorer Forums - Serious Explorations

  • Register Today It's free!

Is this the Oxygen sensor B2S1? Plus questions related with PO153


Well-Known Member
January 7, 2011
Reaction score
City, State
Eden Prairie, MN
Year, Model & Trim Level
98 Explorer
I have engine light on with code PO153. I am going to diagnose it this weekend. I have read many discussions and understand that this may not be caused by the oxygen sensor. But just in case I need to change that I need to know exactly where it is.

See below image taken from driver side. Is it the B2S1 in the middle of the image?


Further questions.

1) Where is the B1S1? I tried to find it from passenger side, I couldn't. Any picture will be much appreciated.
2) Is the B1S1 and B2S1 the same? If it is I can switch it before committ to buy a new one.
3) Where are the B1S2 and B2S2? The truck is 13 years old and may make sense to replae them anyway.

Any other suggestions in diagnose PO153 will be appreciated. I will try to clean MAF and exchange PCV valve. Anything else to look at?

Thanks in advance?

Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!

Thats the correct sensor.

Unless you have a bad exhaust leak, the sensor needs replacing. Chances are the other one is the same but the one on the passenger side is harder to get to. That may be the one that you have to access through the floorboard of the truck.

How do I know whether there is exhaust leak? Any easy way to inspect?

Is your vehicle loud up by the engine? Rotted pipe or anything?

The engine's noise is not that bad. Actualy I didn't notice any change before and after the code shows up. The bottom of the truck is clean and I couldn't find rotte pipe by naked eye.

Then it's the O2 sensor. And it's an easy one to change. I believe it should be 3/4.

Appreciate the help!

Is it considered the downstream or upstream sensor?

There's no way to clean the old sensor with a wire brush or am I just better off getting a new one?

I did change the sensor and that cleared code PO153. I am not sure whether you can use a wire brush to clean the sensor. If the sensor is used for more than 100K, it is the time for replacement.

Yeah good point. Just hope it clears my P1151 code.

Yeah good point. Just hope it clears my P1151 code.

For reference:
Bank 1 is the bank with the #1 cylinder; for both V6 and V8 Explorers that is the passenger side bank. Sensor 1 is the sensor in front of the catalytic converter; sensor 2 is behind the cat.

Good info. Thanks.