2004, 280Kmi Got my first smog notice Wednesday, and of course I got my first check engine light yesterday. Code reader says p0138, which I've researched to point mostly at the O2 sensors. I'll replace the front one first to try to clear the code. How many o2 sensors are there anyways?, just the two? and are they the same? I've searched, but can't find definitive recommended part numbers. Some help please? Thanks, Jay W
That code points to Bank1/Sensor 2, which is the "post" cat sensor. Yes there are two. Not sure if they are the same, but wouldn't think so.
There are two sensors first one (before catalytic converter) B1S1 is special air fuel ratio sensor. Second one (after catalytic converter) B1S2 is just normal 4-wire heated oxygen sensor. Toyota part numbers: air fuel ratio sensor: 89467-47010 oxygen sensor: 89465-47070
Other threads say despite 'showing' rear sensor it's often the front that's bad with this code. Any denso or other parts? Or is Toyota the only one?
