I had my catalytic converter replaced last summer and then the SES light came back on a few weeks ago, just before my DEQ test was due on my registration. I went over to a Schucks and had them run the computer test which reported 0420, the catalytic converter. They cleared the code and I hightailed it over to the DEQ station, where my car passed with flying colors (including the O2 sensor reading). A few miles later, the SES light came back on. So I went back to the place that replaced the catalytic converter and they tested it, with me standing right there. Everything was fine. Does this mean everything is sort of okay for now, except for the pesky SES light? I figure I might have to spring for a new O2 sensor when I have the money, which I won’t for another few weeks…
Is this a Service Engine Soon (SES) light or a Check Engine Light (CEL)
There are service engine lights on some cars and they tell you when they think you should change oil etc. The CEL says the computer had received a signal that something is not normal and should be checked.