I've Mazda Premacy'08 with MZR 2.0 DISI and MIL P2187 error. As I understood first O2 sensor gets too much oxigen passing through and when long terms fuel trim exceeds 20% it turns on the MIL. I'm already checked MAF and possible air intake after it, purge solenoid valve works good. The only idea I have now is to change O2 sensor. OEM code is LF2L188G1B but it is almost same with LFL7188G1B which are used on Mazda3 (BK) and Mazda5 (L7).
Before changing O2 sensor I would like to hear your opinion. In Russia its about 300$ in price and I don't won't to spend it to no purpose.
One other idea - i've PID printout where absolute throttle position is 11%. I've heard that this PID shold be 0%?

 

Tons of info about P2187 was reviewed and before I order new O2 sensor I opened the cowling again this evening and tried to find unregistered air intake one more time. It was surprise when at the bottom of intake manifold I saw some little embossment and moisture around. I put finger there and found split in the manifold. Unregistered air intake was exactly there.
Temporary I closed it with the consruction sticky tape. The result was immediate. Engine became silent in work, no vibration on car body.
Now I think about how to close the split on a permanent base. Thanks.

 

Glad you went back for a second look. I guess the old saying is true: "If at first you don't succeed, try, try again". You were on the right track, but missed it first time. Saved yourself a lot by not buying O2 sensor!

 

You can possibly try some high temp epoxy to seal the manifold up, might last a while longer than tape.

 

I think of cold welding mastic, anyway it is better to remove manifild and see what will be the best solution.
Few photo in attachment.