The engine light was on last week on my 2000 Corolla, local firestone states I need a new catalytic converter for $ 750- Light went out 2 days ago, do I still need it? Is there a test to find out if first recommended service was wrong?
Did the light going out correspond to a fresh tank of gas from a different gas station? I have a friend who had the same problem with her 2003 Corolla. But, we figured it out that the car didn’t like gas for a particular gas station. When she used a different gas station, the light went off and stayed off. She stopped going to the one station.
How many miles are on the Corolla? You might qualify for the warranty replacement within 10 years.
Yes, there is a test. The code is tripped by a comparison between the signals from oxygen sensor in front of the converter and the one behind the converter (“upstream” and “downstream”). A shop can actually display the two signals on an oscilloscope and tell if, in fact, the converter is bad or the downstream sensor is bad.
Since it went out again, you could have the computer checked for stored codes (free at many parts stores) and post them here, or wait to see if it comes back on and have diagnosis performed then. It may have been something simpler than the converter.