2001 Impala SES Code P0420

[Dave]

Got a 2001 Chevy Impala. Autozone scanned for a check engine light.
Code is P0420 catalytst inefficient.
They said I need a new cat. converter.
Have read on some other forums that it copuild be the EGR or Mass air flow sensor, but i don't have codes for those. Can those sensors still be the problem?
48zadnp

[Meccboy]

If either the airflow sensor of one of the oqygen sensors were bad, there would be a code for them.
Even if there were codes for those sensors, a faulty catalytic converter can CAUSE theose codes.
When a converter is plugged, it will affect oqygen sensor readings, as well as the MAF.
This sounds like a bad catalytic converter.

[Guest]

Okay so about 6 months ago we purchased a 2001 chevy impala that had been sitting for a couple years. They did not know what was wrong with it so we got it cheap but the problem is we have never been able to get it to go above 35-40 mph. The security light is on, on the dash we have tried a couple different things that we have found online to reset it but cannot seem to get it out of what ever funk it is in. It starts and runs but it wont shift out of 1st and 2nd gear. Is this a transmission problem or is there something we can do to fix it? That Is cheap and easy? It does have a recall on a part of the car and needs to be serviced would this have anything to do with that? Please HELP any information you can give us is much appreciated as we are on a fixed income at this time and have two babies.

[carriedi]

the security light may be on but if the car starts up and runs I would put that on the back burner for now.

is the check engine light on?

a plugged catalytic converter can cause a problem like this too. Check for excessive back pressure in the exhaust system.