P0420

ofcork

Has anyone ever got one of these codes diagnosed and fixed.

Avns1s

What car?

Catalytic Convertor or lambda sensors.

Ded_Zebra

P0420 - Catalyst below threshold. The code could be triggered by a bad O2 sensor, Bad wiring to an O2 sensor or the cat being worn out.

Car make, model, engine, year etc is helpful though. :rolleyes:

Nissan doctor

In the majority of cases its a damaged catalytic converter that cause that fault.

Diagnosis of the pre and post cat lambda's will confirm if this is the case. And the cause is normally damage to the cat from poor running/misfires etc.

ofcork

Its a 04 avensis 1.6 petrol with 147k miles,some places have said cat and others o2 sensor.

Nissan doctor

ofcork wrote: »

Its a 04 avensis 1.6 petrol with 147k miles,some places have said cat and others o2 sensor.

Has anywhere diagnosed the problem though, by which I mean actually carried out diagnostic tests of the components rather then just scan for a fault code?

On your car the problem can be caused by a worn(slow switching) pre cat lambda sensor. These have a life of approx 100,000 miles so after that their ability to control the fuelling is reduced, eventually damaging the cat.

ofcork

I dont believe so just plugged in laptop and came up with answer.

Nissan doctor

ofcork wrote: »

I dont believe so just plugged in laptop and came up with answer.

Unfortunately pluging a car into a computer doesn't give you the answer, it just tells you were to start looking.

ofcork

Thats why i wasnt willing to get the work done as main dealer last year wanted 500 for cat with 300 labour,the car seems to be using more petrol now so want to get sorted as only got around 33mpg on last fill.

ofcork

Can anyone recommend a garage/mechanic in cork who would actually test the sensors/cat etc thanks.

Nissan doctor

ofcork wrote: »

Thats why i wasnt willing to get the work done as main dealer last year wanted 500 for cat with 300 labour,the car seems to be using more petrol now so want to get sorted as only got around 33mpg on last fill.

Unfortunately, having left it so long, you will likely now need a new cat and a pre cat lambda sensor and only genuine Toyota Lambda sensors will work correctly.

ofcork

Surely could still avoid main dealer though?

Nissan doctor

ofcork wrote: »

Surely could still avoid main dealer though?

There is no reason to have to use a dealer at all. Any competent garage could diagnose and repair it for you.

johnayo

ofcork wrote: »

Surely could still avoid main dealer though?

Good indie could do this no prob. But as the Doctor said... Genuine Oxygen sensor should be used. Toyota's don't mix well with the aftermarket ones.

PADRAIC.M

Just to point out on the pre 2005 Avensis there was a logic fault in the engine ecu to cause p0420, fix can be a cat AND an ecu or you could have p420 again in 6months, depends on ecu part number and whether throttle is cable or wire driven.

ofcork

Didnt have any problems all along,even passed nct last year just lately noticing the drop in economy.

joujoujou

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2215704#Post2215704 - I'd say quite good and complete explanation of checks to be performed.

ofcork

Now to actually find an indie who will actually do this!