P219B Code - Bank 2 Air-Fuel Ratio Imbalance

Guys,

2013 Tacoma V6 - 4.0L with 153,700 miles. Yesterday morning, my Tacoma produced Check Engine Light and Trac Off. Since I do not carry my OBDII reader, I went to O'Reillys and borrowed one of their scanners. It returned a P219B Code - Bank 2 Air-Fuel Ratio Imbalance - Replace Cylinder Head Assembly. The engine runs perfectly fine. It is idling smoothly, and acceleration feels normal. Based on that, I hope this is just a fluke.

Being optimistic and not pessimistic, I hope I can resolve this issue without removing the cylinder head. I read a few threads on this site that suggest trying a few things. One of the questions I have is, which side is Bank 2?

That said, I am going to clean the MAF sensor. I am also considering replacing the air/fuel ratio sensor on Bank 2 with a Denso / Dealer brand.

On December 2023 with 144,000 miles I replaced the spark plugs with DENSO brand.

If the CEL comes back, my plan B would be to replace the intake manifold gasket. The guy at O'Reilly's suggested replacing them.

This is what I can think of as a starting point.

Has this issue been resolved?

 

this code only pops up on the 2012-2015 trucks.
And it isn't too easy to diagnose.
It's a air/fuel issue. I don't have a lot of knowledge on it.
But it seems it's usually a cylinder head flow issue.

Step on would be look for exhaust leaks.
Then it gets more difficult to diagnosis if that isn't it.

The thing is, most trucks only fail by a small error. And it never gets worse.

See the link below. See post 2 for Service Info (FWIW, it's not very helpful as to diagnosis)
https://www.tacomaworld.com/threads/p219a-p219b.840160/

 

If it is an anomaly with the system and not an actual fault,
as a worse case scenario, hail mary, last resort, anything to make the annoying CEL light to go away
you could try wrapping one or both of the O2 sensors with stainless wire to trick them into a lower overall or more balanced reading, this worked to get "some guy I heard of" with a stubborn CEL O2 code to go away forever and make it through a State Emissions inspection , it might help in this case.
makes no sense to change an intake gasket if there is no leak , an intake vacuum leak should show up on a vacuum gauge as a vibrating needle, (not steady)