I have a 2009 matrix with the 1.8l engine. Roughly 99k.
I replaced the downstream o2 sensor because I got the code PO138. Cleared the code and then roughly 70 miles later it came back on. Now I have the code PO138 still, and PO136 in addition to the code I had in the first place. Would resetting my ecu help, or do I need to change the second one now?
what is the full trouble code definition please?
Realize the oxygen sensors part of a complex feedback computer driven system it could easily be that your catalytic converter has a problem I would change the other sensor first but they work in conjunction with the catalytic converter and once they trip a cold they stop analyzing if you fix that one code and there's further problems then it will trip more codes it's not that easy to diagnose unless you find a professional mechanic like me to do some serious on board analysis after a road test but you could guess with a sensor
Clean the MAF sensor and check for vacuum leak. Then clear the codes and see what happens.
