I have to admit that this is not about the Chrysler, but this is one of the better newsgroups for information. So I hope nobody minds that I ask.
We are considering buying a car that has the "check engine" light on. Anticipating that this might be the case when I went to look at it, I brought the handy code scanner with me.
The scanner said o420. The code description is "Catalyst System Efficiency Below Threshold (Bank 1). What I have been able to determine, so far is that either:
- The downstream O2 sensor is misreading the output of the catalytic converter or
- The catalytic converter isn't doing it's job properly, which the O2 sensor is correctly reporting.
The car is a 2000 Mazda Protégé with about 115K miles on it. Thanks in advance.
Ken