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Seat Ibiza 1.2L 2004 - MIL on, code P0420 Catalyst efficiency #

Posted by Malcolm Crosbie on December 2, 2010, 4:34 pm

Year of Manufacture *: 2004
Engine Size and Code *: 1.2 l 12v
( Optional ) Scanner Used: Modis
( Optional) Fault Codes: P0420

Car is in with eng management lamp on checked out and only code listed was P0420 catalyst efficency below threshold volkswagen code 16804 had this code before on a seat and never got to the bottom of it and they seem to have a complex lambda sensor setup on them, we fit a cat to the last one but it did not stop problem any help would be greatley appreciated.

As you can see I have uploaded freeze frame data image this fault only occurs now and again thanks again Malcolm

Re: Seat Ibiza 1.2L Catalyst Efficency P0420 lamp on

Posted by Peter Warman User icon on December 2, 2010, 5:04 pm, in reply to "Seat Ibiza 1.2L Catalyst Efficency P0420 lamp on"
Peter Warman - Administrator

Hi Malcolm

Were they aftermarket or genuine dealer cats

Have you checked the gas readings at idle and fast idle, you need to eliminate the cat efficiency before you look further

Gas readings plus front and rear o2 sensor waveforms would be good. Have a look at fuel trims to see if its adding or taking away fuel

Peter

Re: Seat Ibiza 1.2L Catalyst Efficency P0420 lamp on

Posted by Malcolm Crosbie User icon on December 2, 2010, 5:35 pm, in reply to "Re: Seat Ibiza 1.2L Catalyst Efficency P0420 lamp on"

It was an aftermarket cat that we fit the last time I have checked the emissions and they seem to be fine its just the front lambda sensor has 5 wires and autodata does not give me much info not sure which to scope thanks again.

Re: Seat Ibiza 1.2L Catalyst Efficency P0420 lamp on

Posted by Mark Carter User icon on December 2, 2010, 6:27 pm, in reply to "Re: Seat Ibiza 1.2L Catalyst Efficency P0420 lamp on"
Mark Carter

Hi, What are the fuel trims telling you?

Regards Mark

Modern cars, Its all wizardry and witchcraft

Re: Seat Ibiza 1.2L Catalyst Efficency P0420 lamp on

Posted by lee woods User icon on December 2, 2010, 10:31 pm, in reply to "Re: Seat Ibiza 1.2L Catalyst Efficency P0420 lamp on"
Lee Woods

Check the after cat lamda at cruise speed the reading should be steady at about 0.7 volts or above this shows that the cat is efficient and burning all the oxygen.

I have seen after market cats that will pass mot test ok but the engine manangment flags a catalyst inefficient code due to seeing to much activity on after cat lamda .

Gas readings on a good cat 0.0 co

lamda 1.020

Some of the after market cat only get the co down to 0.2

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