Hi, I sorted this way as well
Hi, I sorted this way as well.
Firstly I changed second sensor to denso dox-0269 and code P-0136 and P-0138 still was come up every 30 or 40 miles trip.
Also fuel ratio was 15.2:1 instead 14.7:1 , which is to rich.
Voltage stayed on sensor 2 0.8v on idle ,but was responding to throttle.
Was bothering me for 9 months and it was annoying to reset everytime.
All wiring looks like brand new without damage on My yaris 2009 UK version and heater cores on sensor shows resistance on 1st and 2nd pin .
Interestingly enough, then I remove 1st sensor, it looks contaminated with white colour ,but engine work fine and car done only 77000 miles and not oil burning between oil changes at all.
Resistance on heater cores 2.5 ohms and on new denso dox-0510 sensor 3 ohms.
I believe that sensor still works ,but is contaminaited and some cleaner would help ,but changed anyway.
Thank you for your post and hope it would help for other with the same problem.