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Gallagher99
Gallagher99, Senior Vehicle Technician
Category: Car
Satisfied Customers: 3280
Experience:  SVQ LEVEL 3, QAULIFIED FORD SENIOR TECHNICIAN , ATA REGISTERD ,12 YEARS EXPERIENCE
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Ford Fiesta MK V couldn't pass emission test. P 420 some

Resolved Question:

Ford Fiesta MK V couldn't pass emission test. Cod P 420 some times could be seen on the scanner, but one time in month . Replaced O2 sensors but emission still above required.
Submitted: 2 years ago.
Category: Car
Expert:  Gallagher99 replied 2 years ago.
Hi there good evening to you and sorry for the delayed response
Ok the fault lies with the catalitic convertor
P0420 is a catalyst efficiency below threshold indicating the fatalist isn't working properly
This is most commonly caused by a previous engine missfire causing Raw petrol to enter the Catalyst and damage it
The only way to correctly resolve this issue is to replace the catalyst
You can extinguish the light but it will come back on with the same code
If you need anymore help or advice on this issue please let me know
If you are Completely satisfied with my answer /advice
PLEASE RATE MY ANSWER
Kind regards ***** ***** and have a nice evening
Brian
Gallagher99 and other Car Specialists are ready to help you
Customer: replied 2 years ago.

Hi , Thanks for your replay.

Yes car had misfire. One of HT leads had fault, but it was rectified only in two month time. Is it single way to repair fault ? Is it possible to clean catalyst ?

Expert:  Gallagher99 replied 2 years ago.
Hi there
Ok the catalyst cannot be cleaned to resolve this issue
the Only way to resolve the P0420 code is to replace the catalyst which is damaged internally due to the previous misfire
If you need anymore help or advice on this issue please let me know
If you are Completely satisfied with my answer /advice
PLEASE RATE MY ANSWER
Kind regards ***** ***** and have a nice evening
Any positive feedback or bonuses are greatly appreciated
Brian
Customer: replied 2 years ago.

Thanks,

How much could cost it ? What is best options to replace it.

Vic

Expert:  Gallagher99 replied 2 years ago.
Hi vic
Ok the best option is either a second hand catalyst or a new one which is a few hundred pounds (more expensive for a genuine ford one
Regards Brian