P420 (reason for SES light)

[Mustang Val]

So, AutoZone checks the stupid a** computer, seems it is a "P420" which, as they explained means the catalytic converter isn't getting hot enough. Any ideas as to what it may be to fix such a silly thing (blow torch on converter?.....kidding).

Thanks for any ideas,
Val

[rigs]

Here are some possible causes and some diagnostic aids.
Have you disconnected the battery like for 20 min. and still give this same fault??

P0420 - Catalyst : Indicates Bank 1
: * Use of leaded fuel : - Compare HO2S :
: System Efficiency : catalyst system : * Damaged HO2S : upstream & :
: Below Threshold (Bank : efficiency is below : * Malfunctioning ECT : downstream switch :
: 1)
: the acceptable : * High fuel pressure : rate. Under normal :
: : threshold : * Damaged exhaust : closed loop fuel :
: : : manifold : conditions, high :
: : : * Damaged catalytic : efficiency :
: : : converter : catalysts have :
: : : * Oil contamination : oxygen storage :
: : : * Cylinder misfiring : which makes the :
: : : * Downstream HO2S : switching frequency :
: : : wires improperly : of the downstream :
: : : connected : HO2S quite slow :
: : : * Damaged exhaust : compared to the :
: : : system pipe : upstream HO2S. As :
: : : * Damaged muffler : catalyst efficiency :
: : : /tailpipe assembly : deteriorates, its :
: : : * Retarded spark : ability to store :
: : : timing : oxygen declines and :
: : : : the downstream HO2S :
: : : : signal begins to :
: : : : switch more rapidly :
: : : : approaching the :
: : : : switching rate of :
: : : : the upstream HO2S. :
: : : : Once beyond an :
: : : : acceptable limit :
: : : : the DTC is set. :

[Ponycarman]

What the code means is that the computer doesn't see the cat as having the desired effect. Why that is so is to be determined. Rigs listed a bunch of possible causes you'll have to eliminate them to confirm the failed component.

Steve