The check engine light came on in my 2001 Subaru Outback. My scanner indicated a problem with my catalytic converter. I used the scanner to turn off the check engine light and took the car for an emmisions test. The car passed the test. The light came on again and the scanner again indicated a problem with the catalytic converter. Since the car passed the emmisions test, I don’t believe I need a new catalytic converter which would be quite expensive. I am thinking there might be a problem with an oxygen sensor. I want to keep the light from turning on. Is ther a way to check the oxygen sensors ?
This might seem like splitting hairs; but, the DTCs your scanner revealed do not indicate a problem with the catalytic converter. They are diagnostic codes of the emissions system. The difference in meaning? Only several hundred dollars for replacing the wrong parts, and, perhaps, still not fixing the problem.
Someone will always say, “I changed a bunch of parts, and fixed the problem.” Yeah, luck happens; but, at what price?!
What happens at the front of the engine (intake, combustion, etc.) affects what happens at the the back (oxygen sensors, catalytic converters, emissions).
A scan tool, or an oscilloscope, or a gas analyser can check the oxygen sensors. The engine computer does a check of the oxygen sensor, also.
Bring the DTCs (diagnostic trouble codes) here for interpretation and advise.
Thanks for the info. The autotap link on this page has a video on checking the oxygen sensors. I will try that method when the wife brings the car home tonight.