code po420

[LiqiuidWrench]

Hello everyone,
My 1995 Lesabre check engine light came on. Ran a scan, code po420
Catalyst system efficiency below threshold [bank 1]
Would someone please tell me what this means. Is my catalyst converter bad by being plugged up thanks in advanced. Car has 210,000 miles on it

[maxwedge]

There is lots of info on this code both as a google search and a site search, most times the cat is bad, but other issues pop up here, a skewed post cat sensor is another possibility, there are several tests to pin down the code, do a site search first.

[LiqiuidWrench]

Thanks Maxwedge,
For giving me help on where to look. I ran another scan and a new code poped up po406 exhaust gas recirculation valve position sensor a circut high. Any help on this would be appreciated .Thanks again

[HotZ28]

Click Here for some info on how to clean the EGR. Have you ever replaced the cat? If not, with 210K miles, more than likely it is clogged. See the pics below showing how the catalyst can become blocked and how it can restrict flow when broken.