Originally Posted by
howardc64
If end of life, then you have nothing to lose to give a couple of tries a couple of simple+cheap fixes
DIM - Get an electronic tech with good tools to reflow solder around the motorola chip. This fixed quite a few crazy dashes.
CAT - If not plugged (back pressure) Remove and soak+agitate in citric acid solution for 8 hours (google for what solutions people use). I've heard this fixed a few P0420 code on Prius. I guess it exposes the catalytic material by cleaning the gunk coated on the reaction surfaces. Alternatively you can put a O2 extender on the O2 after the CAT to fool the emission system to think CAT is doing its job. Quick note on the O2s, pre CAT O2 adjusts air fuel mixture for lean+rich. post CAT O2 just confirm exhaust after CAT removed the stuff harmful for environment. Extending post CAT O2 pulls it out of the exhaust stream and makes it think its clean. I think people even put in fake circuit on the post O2 wire to fool the emission system. But of course this is against the emissions law and pollutes the environment.