Yaris engine code P0420

cbrpaul

just had a MOT emissions test, by a friendly local garage !!

results

fast idle
CO limit < 0.30% actual 0.38% =Fail
HC limit < 200ppm actual 24ppm = pass
lambda limit 0.970 - 1.030 actual 1.021 pass

Natural idle
CO limit < 0.50% actual 0.49% pass

So it seems its now failed on fast idle CO and ok on natural idle CO !!

I did put a fuel/engine cleaner in 10 days ago, maybe this has done some good ?

The guy who did the emissions test also said that if it was an actual MOT he is 100% sure he could get the fast idle CO fail , to eventually pass through a test !!

He also said the Lambda`s appear to be doing their job !!!

He said the cat could be slighty clogged due to the car doing short journeys as it has only done 2000 miles in one year !!

He recommended some " cata-clean" in the tank along with a Italian tune up the motorway !!!

failing that , a new cat along with x2 new lambda`s :eek:

forgotmyname

You need to get someone to check it properly not just a appear to be working and then saying a new CAT and 2 sensors.

Are the sensors heated? Heaters working? How many wires?


What about the service history? Plugs/leads fuel filter?

tedted

you are doing such short mileage the cat is not getting lit give it a good blast and all will be well

cbrpaul

I plan on popping some "cataclean" in today and going for a 20 mile Italian tune up on our local 2 mile stretch duel carriageway, a few times

It had plugs , oil, oil filter, air filter , all done 2 weeks ago ,

Sensors are 4 wire, I have sourced them for £55 each direct fit, from a reputable online company, dealer wants £130 each:eek:

the guy said I can pay a auto electrician to fully test the lambda`s for £35ph , or just replace them anyway !!

I like to my own diy on cars if possible, but Problem is the lambda`s are probably stuck fast in the manifold/cat , and knowing my luck when I attempt to remove them , the threads will strip needing a new cat then as the cat is integral to the exhaust manifold !! :(

tips on removing stubborn lambda`s anyone ? :o

mattyprice4004

Did you not read the previous posts?!
Snake oil cat fixes don't work - once it's knackered it's knackered.

Take it for the Italian tune up, if that doesn't work it's time for a new cat.

forgotmyname

cbrpaul wrote: »

I plan on popping some "cataclean" in today and going for a 20 mile Italian tune up on our local 2 mile stretch duel carriageway, a few times

Waste of money.


Sensors are 4 wire, I have sourced them for £55 each direct fit, from a reputable online company, dealer wants £130 each:eek:

the guy said I can pay a auto electrician to fully test the lambda`s for £35ph , or just replace them anyway !!

Or buy a £5 test meter and test them yourself?


I like to my own diy on cars if possible, but Problem is the lambda`s are probably stuck fast in the manifold/cat , and knowing my luck when I attempt to remove them , the threads will strip needing a new cat then as the cat is integral to the exhaust manifold !!



tips on removing stubborn lambda`s anyone ?

Heat and WD40. Spray whilst cold and let it do its work, Get it hot and then spray it again, When its cooled spray it again and repeat.
Do that 2 or 3 times and it will undo easily.

message too short..bah.

cbrpaul

did some digital meter tests this morning with my Fluke meter

results

pre cat sensor

heater circuit 8.5ohm
Signal at operating temp at Idle 400mv
Fluctuates upto 800mv when rpm raised


post cat sensor

Heater circuit 8.7ohm
Signal at operating temp at Idle 120 - 60mv
Fluctuates upto 600mv max on raised rpm

General rule of thumb for sensors is , 1v o/p from sensor = rich , 0v o/p from sensor = lean

So if the post cat sensor is reading lean would this tell the ecu to add more fuel , and give the high CO readings that I get on MOT tests ??

forgotmyname

Check for air leaks and any exhaust leaks next.

cbrpaul

had exhaust system all checked up on lift, all pipes checked for air leaks , all good !!

One thing the mechanic said was that the engine was little lumpy on idle, once warmed up , could this also confirm a failing lambda ?

As the lambdas only come into play once the engine is warmed

cbrpaul

UPDATE :

I just want to update this thread in case someone is searching it the future

I had a emissions test today and the results were

CO limit <0.30% actual 0.15% PASS
HC limit 200ppm actual 4ppm PASS

SO what did I do !!

I soaked the cat in hot Citric Acid for 6 hours !!!!!

I decided to research the web and found that a University in UK and USA did some tests on failed cats, in the fact of trying to bring the precious metals back to full capacity.

The tests they did was to soak the tired old cat for 6 hours in a hot bath of Citric acid.

The acid dissolved all the foreign metals and contaminants but didn't harm the platinum or palladium precious metals within the cat.

SO I bought 0.5kg of powder Citric Acid for £5 and it worked !!

The tester couldn't believe it :rotfl::rotfl:

So don't throw that cat away , simply revitalise it for £5 !!!! and saved myself £400 for a new catalytic converter