For leaks in the evaporative emission system, it depends on the code. For big leaks, look for hoses disconnected, loose gas cap, etc. For small leaks you really need a smoke machine. That allows you to inject white non-toxic smoke at 2 psi, then you search for where it's sneaking out.
There are a lot of oxygen sensor codes. The course of action depends on which code and for which sensor.
August, 9, 2012 AT 11:18 PM
O2 sensor code is po141 1/2 heater permformance? Is this the rear o2 sensor bank one sensor 2?