2003 Chevrolet Impala

Engine Performance problem
2003 Chevy Impala 6 cyl Front Wheel Drive Automatic 157000 miles

It just started 3 days ago and getting worse. OBD2 reads code P0420. From 20 to 50 mph it seems to have a loss of power when I step on the gas. Do you suggest with code given the catalyst converter needs to be replaced?
November 13, 2008.

Yep; the code and the lack of power at higher speed are typical of a plugged converter resulting in excessive back pressure.
Check exhaust backpressure to makes sure.
In your case it went bad probably because it had 157,000 miles on it, however a bad converter is sometime the result of another problem such as worn exhaust valve, leaky head gasket, cracked cylinder, bad coolant sensor, etc.

Nov 14, 2008.
I have a 2003 chevy impala no code are on but it loss power when I step on the gas what can be the problem.I tried this egr valve mass air flow sensor tps coils ignition control module what can it be please need help

Sep 13, 2011.
Check the fuel pressure. There is a test port on the fuel rail. Auto Zone or Advance Auto has fuel pressure test gauges they will loan out if you give them a deposit.