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Guest Message by DevFuse

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P0420 Fault Code help needed


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1 reply to this topic

#1 Paul-H

Paul-H

    New Fiesta Member

  • Fiesta Forum Member
  • Pip
  • 2 posts
  • Region:European Union
  • Location:Kent UK
  • Current Vehicle:Fiesta Zetec

Posted 11 April 2017 - 12:05 PM

Hi all

Had this problem with my 2003 1.4 Fiesta for some time but now getting round to try and fix it 

for the last 40k miles every 500 miles or so the EML pops on with an error code P0420 Catalyst System Efficiency Below Threshold (Bank 1)

So how do I find what is the route to the problem, I assume either one or both o2 sensors or the cat itself could be at fault, all quite pricy on a car this age so don't want to go down the try and see route.

How do I test the sensors to double check they are at fault.

I have monitored the sensor voltages whilst driving assuming that this would indicate if one or both is not working or if both have the same reading I understand that would indicate the CAT has failed.

I used Torque to log the data but can only get it to send screen captures not the whole logg 

Looking at the three attached captures do they indicate anything obvious

Thanks for any help resolving this

 

 

Attached Files



#2 Paul-H

Paul-H

    New Fiesta Member

  • Fiesta Forum Member
  • Pip
  • 2 posts
  • Region:European Union
  • Location:Kent UK
  • Current Vehicle:Fiesta Zetec

Posted 13 April 2017 - 05:24 AM

Can anyone help with this
 
Thanks
 
Paul







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