'03 Impreza Outback,automatic, 2.2L, 182K miles. Recent purchase...maybe 400 miles. Advance Auto computer says something like "emission control not at full efficiency." Young man who tested says try some fuel treatment and light may go off.I had a bottle of Techron on hand so put it in today. Is is likely that his..or Lucas, or Seafoam might actually "fix" the problem ? With 182K I'm pretty skeptical and thinkinh maybe big bucks...cat converter may be toast ? Any thoughts or suggestions would be appreciated !

I think they mean the O2 sensor. You are due for a new front one. O2 sensors do erode over time and need replacement. What he said to you was the ever popular "lets sell this sucker a 1000.00 cat when he needs a 150.00 (from the dealer) O2 sensor.

Really need an actual P0XXX code if you can get it.

 

"Catalyst efficiency below threshold" is the closest I can find to the parts guys statement.