gs450h code p0420 came up! help!

[carnut1980]

P0420 LEXUS - Catalyst System Efficiency Below Threshold Bank 1  

 

  Apparently Possible causes are:

Three way catalyst converter Bank 1

Exhaust tube Intake air leaks

Fuel injectors may be faulty

Fuel injector leaks

Spark plugs may be faulty

Improper ignition timing Engine Control Module (ECM)

I also read somewhere else that it could be a cat converter.

car is a high mileage 2007 gs450h, new MOT, full lexus SH, recent service, runs perfectly, but the EML did light up the other day, i read and cleared it, but surely if it lit up and this code showed, then there could be a minor issue?

What should i do first? Give it a good motorway run? Or perhaps add some injector cleaner into fuel?

If its an oxygen sensor, which one? I have techstream software somewhere, would that tell me?

cheers guys/girls!

 

[Britprius]

If you have Techstream this should give sub codes to the P0420 code and point you in the correct direction.

John