P0420 & P0430 Codes

[stubby_kay]

Hello all,

I'm new to this forum and need some help please.

Recently bought a GS300 2006 model and having driven about 350 miles home I stopped for fuel and when I set off again the engine warning light came on followed by a check AFC light.

I connected a diagnostics tester and have codes P0420 & P0430 which is telling me both front cats aren't working well.

I don't have any funny smells from the exhaust which makes me think the cats are ok and it seems strange to have both cats faulty together.

I have purchased a service manual and it shows a charcoal canister fitted under the rear of the car but I'm thinking this might be just for the US cars and not the UK cars - does anyone know if this assumption is correct.

Any help would be appreciated please?

[TigerFish]

Try tightening up the fuel filler cap and see if that sorts it. Quite a common gotcha which is hopefully a quick and cheap fix for you :)

[stubby_kay]

Thanks for your reply, tried that already, even tried different fuel (non-supermarket) but still the same

Do you know if the UK GS300 has the charcoal canister in the emissions system and if so, where?

[steve2006]

If you have a friendly MOT station nearby it may be worth asking them to stick the emissions probe up the tailpipe and check the readings.

[scudney]

Could be your exhaust could be blowing every so slightly?

[stubby_kay]

Could a hole in the exhaust further down the system cause this fault?

It's been welded (badly) where the exhaust branches out to the two tail pipes, but doesn't sound like it's leaking

I'll check it for leaks - thanks for your help

[scudney]

Yes it can,even if its just as small as a pin hole,depending on how close it is to the sensors could trigger your engine management light to come with the P0420 fault code(when read with a code reader)

[stubby_kay]

Thanks for the help all