Obd Codes P0420 And P0430

[bprior]

I have a 2002 Toyota Rav4 (gas engine) with 261,000 km. In the past I found diagnostic codes P0420 and P0430 (P0420 Catalyst system eficiency below threshold bank 1,

and P0430 Catalyst system eficiency below threshold bank 2) so I took it to my Toyota dealer. They replaced some sensors and my bill was over $600 CAD.

In more recent times when the engione light has appeared I have just downloaded and cleared the codes, the engine light has gone out, and I have kept driving. Gas mileage hasn't changed.

In the past month the light came on again and the engine has become increasingly noisy, particularly in acceleration. It sounds like a sticky valve, or something else that kind of ticks or knocks. When cold it's very noticeable; it smooths out somewhat after driving for 5 or 10 minutes but doesn't go away.

I understand that Toyota issued a bulletin in 2005 concerning these emission system codes. I haven't been able to get a copy.

Would anyone on this forum know where Toyota Service Bulletins can be obtained on the internet?

Does anyone have any knowledge of long term effects of driving with malfunctioniong emission control sensors?

Many thanks for your help.

Bruce Prior

Burnaby BC, Canada