P0134 Code... Which O2 sensor is bank 1?

[smetzger]

So, pulled a CEL with a P0134 - O2 sensor No activity, Bank 1, Sensor 1

Which O2 Sensor is this?
Is it the upper one or the lower one?

Thanks,

 

[915_P5]

Should be before the primary cat

 

[MrGiggles]

Upper, on the manifold.