What does Code P0420-Catalyst System Efficiency Below Threshold (Bank1) mean?

 

Means your cat is on it’s way out. That or your o2 sensor.

 

OK, I cleared the code and the engine light came back on after about 2 days of regular driving.

This is the what my engine shows at normal operating temperature:

O2S
At Idle 680 RPM/ 1500 RPM
B1 S1 0.305 /0.720
B1 S2 0.130 /0.115
B2 S1 0.780 /0.380

MAF:
0.775 /2.152

Any suggestions?

 

If you are not concerned that the cat is not doing what it is designed to do, install a MIL eliminater in the oxy. sensor wire harness.Just a jumper harness plugged in between plug to oxy. sensor(fools PCM).The only way I have cured this code and it stayed away was to replace the cat OR if Ford has an update for this code-reprogram PCM to latest calibration.96 was the first year for OBDII and don't recall ever having a TSB For updateing PCM to cure a P0420.(did alot of Crown Vics though) Google MIL eliminater for more info! lol Blue

 

Thanks. I will look it up.