OBD2 codes and shut down

[DieselMan]

Vehicle: 1999 Mits Eclipse non turbo RS

Today my vehicle shut down and the oil light came on. I popped the hood and it had plenty of oil and coolant. My scanner first said OBD2 420 after it had cooled down a bit. After driving for a bit I stopped and it read 1420.

420 = Catalyst System Efficiency Below Threshold (Bank 1)

1420 = Seems to be related to an O2 sensor

Anyone come across this or any thoughts on what direction to go?

Topic

[Mike]

So the oil light only came on after the car stalled?
If so, that’s normal. Trouble indicator lights usually come on when the car stalls, just as they do when you first start the car–but they’re not indicating a particular problem.
It would be concerning if the oil light came on before the engine stalled.

Not clear to me if the car restarted right away or not.
Does the car start and run now?

As for the 2 “different” codes, it seems likely that you misread the code reader at some point, since the last 4 digits are identical.
A stored code wouldn’t disappear on its own without being erased.

It is possible is that the computer is malfunctioning, which is a fairly common problem in this generation of Eclipse.

Since you have a scan tool, if the car runs, warm it up so it’s in closed loop and look at the oxygen sensor readings and fuel trim readings.
The O2 sensor 1 reading should be constantly,rapidly changing from the low hundreds to the upper hundreds.
In contrast, the O2 sensor 2 reading should be rather steady.
There should also be readings for short term fuel trim and long term fuel trim.
Record these at idle and then while holding the rpms at 2500 for 30 seconds or so, record those readings
Post them and answer the questions I’ve asked and we can probably help you learn what’s going on.

[Author]

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