Where are the oxygen sensors located at on a 07 Prius base model. Are they easy to replace or would you take them to a shop to get them to change them?
Welcome to PriusChat!! The search feature has been fixed and is currently working (again), you shouldn't have any problems finding pictures and various methods for extraction. The upper A/F sensor (before the cat) is somewhat buried and requires a fairly thin walled socket for removal, the lower oxygen sensor (after the cat) is easily accessed and one can use a standard socket for removal. How many miles on this prius?
Here is the workup for DTC P0171 and P0172 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8CPDF%E6%A0%BC%E5%BC%8F/Prius%20Service%20Manuals%202004/%E4%BF%AE%E7%90%86%E6%89%8B%E5%86%8C/04pruisr/05/2054m/cip0171.pdf There could be other codes unavailable to your current ODB2 device, what kind of OBD2 reader are you using?