2014 Prius code P0420 , should I worry

Your catalyst is failing the flooding self-test that it runs whenever it runs That's that You need a new Toyota catalyst or unapproved catalyst from the US EPA to fit on that car to get the light in the code to go away You might could put two cheap cats together and come up with something but I'm not tried it personally works on other cars.

 

Yes a new one will take a dump fairly quickly if the oil control rings and things haven't been fixed which generally they don't get fixed You just replace the engine with the updated parts like with a gen4 engine which supposedly has all these fancy new parts that are going to eliminate this if you can believe those sort of things then that's generally what you're looking for but to do that in this car is going to cost you a good chunk of change unless you can do it yourself and generally if you could most people wouldn't be here messing around talking too much that are being the garage up on a lift or something this is the same thing as a Corolla edge You can't use a Corolla engine because it's not Atkinson cycle and all that but it's the same basic design of engine with the correct parts in it that doesn't have the oil burning problems low tension rings and all this sort of thing that was made just for free as people planned obsolescence is a mofo.

 

A litre every 5000 miles is “moderate”, still. Hey Toyota says in owners manual anything less than a quart every 600 miles is ok. Ballsy company.

new catalytic converter and for the engine, new short block, have a machine shop go over the head, reassemble with the Toyota gasket kit (includes head gasket), new head bolts. Be sure to clean intake manifold and EGR components (and repeat every 50k). Consider a decent oil catch can install too.

the joys of Gen 3.

 

A new short block from Toyota is between $18-2100, depending on where you are.
Hybrid pit sells a remanufactured ENGINE starting at $1900 I think it was. And up to
$2400(?). That's including the head. So what's the better deal?
And it's a LOT less work to replace the whole engine then a short block.

 

Yeah $1800 and $2100 USD currently:

Engine - 2012-2015 Prius (Gen 3) - PRIUS - TOYOTA

plus shipping, obviously. And OP is in UK.

There are pros and cons. A short block is brand-new. That's worth something, if only peace of mind.

I tried adding a bronze engine (their base option) to a shopping cart, filled out all my info, and it keeps saying that shipping is "not yet calculated". The only option I can see to find out the shipping is to click the "place order" button, and there's no way I'm going there, lol.

 

You don't have annuals on your cars do you in the UK so then no emissions testing and the like so you should be able to just let it rip until it doesn't or cut out the cat so it can't plug up completely but in a pipe You should be legal if you're not then you're not then you have to replace the cat because you have to get the light out and pass emissions I don't have to pass emissions