Toyota Yaris 2001 1.0 - OBD code P0420

Honest John Back Room » Technical matters
View Threaded
Sun 15 May 2016 18:49
Toyota Yaris 2001 1.0 - OBD code P0420 - carman999

On my gf's car this code appears after about 15 miles.

The car starts and runs fine. Air filter is new. The plugs are the correct shade of brown, I've checked the MAF sensor which is perfectly clean and fitted new lamda sensors (2).

I drove it about 20 miles and engine light did not come on. When gf drives it light comes on after about 15 miles.

Previous owner used it for short journeys. GF just bought it.

I'll take the engine round to 4000-5000 rpm, gf probably 2500 max.

Cat partially blocked?

Will Italian tune-up clear the problem? Or is new cat required?

Reply | Report as offensive | Link
Sun 15 May 2016 18:57
Toyota Yaris 2001 1.0 - OBD code P0420 - Railroad.
First things first. This code is set when the pre and post O2 sensor readings are too similar. More often than not a new catalyst is required, but I would first try some Cataclean or something similar and hammer the car up the road.
Reply | Report as offensive | Link
Sun 15 May 2016 19:06
Toyota Yaris 2001 1.0 - OBD code P0420 - elekie&a/c doctor

As above,problem with the cat.However you will probably find that the emmisions for the mot test will be ok for a pass.

Reply | Report as offensive | Link
Mon 16 May 2016 07:28
Toyota Yaris 2001 1.0 - OBD code P0420 - madf

Son had similar problem. Cat had small gas leak around welded jounts - corrosion . Check and seal if found. Son's lasted another 12 months after sealing..

Edited by madf on 16/05/2016 at 07:28

Reply | Report as offensive | Link

Looking for a garage you can trust? Honest John's Good Garage Guide has thousands of reader recommended garages, plus how-to guides and tips on servicing.

The Good Garage Guide