1996 Roadmaster Wagon P0420 CEL

[96LT1]

Hey All,

1996 Roadmaster Wagon with the LT1 Engine (multi port injection) is throwing code P0420. I had the code pulled and the description is "catalyst system efficeny below threshold bank 1."

This code came up a couple months back when I had a fuel pump failure. However I had it cleared while it was in the garage and it has just come back recently. Fuel pump replacement was around 3,000 miles ago. Furthermore, the car has recently become hard to start while cold. Sometimes while warm as well but mostly cold. I'm wondering if the hard-starting is tied to this code.

Also looking for any detail anyone can provide on this specific code as it doesn't seem to point to any specific part such as an oxygen sensor.

Thanks!
James

 

[buickwagon]

The post-cat O2 sensor signal is not ideal. This can be caused by a lazy sensor or a high-mileage cat converter that is no longer efficient. It's an emissions issue, not a running issue.