I have toyota Sienna 98 Replaced the O2 sensor and Ck engine light cokme again for same code PO155. Erased the code severalt times still comes back.
Is Disconneting the EFI Relay will erase the code ?

Which 0xygen sensor did you replace exactly? No to the EFI relay question.

Which 0xygen sensor did you replace exactly? No to the EFI relay question.


Bank2 Sensor 1 ( there are two in front and this is Rear one - which is kind if Hard to Reach ) before cat
What possible solution be ? I have already replaced the front and donwstream before. I used to get code PO133 before then I replaced the front Maifold and Code cleared but this rear one PO155 even after replacement still come on after short drive .