Ford Fiesta (2002 - 2008) - 2003 1.25 Emissions Light On (P0420)

Honest John Back Room » Technical matters
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Thu 2 Apr 2009 10:51
2003 1.25 Emissions Light On (P0420) - Venkman
I am suffering problems with my 53 reg Ford Fiesta 1.25 Finesse, whereby the emissions light keeps coming on.

Initially the fault was diagnosed by the recovery service as requiring a new Cat, which has been installed, the garage also advised of requiring a new O2/Lamda sensor, which has also been installed. However, since the work was performed I have had reoccuring problems with the emissions light coming on.

I took the car back to the garage after having the recovery service diagnose P0420 O2 sensor (Bank 1). They fit a ford authentic part, but once again after 10+ miles the emissions light comes on again. The car seems to drive fine though, does anyone have any previous experience of a similar problem?

Thanks for your help!

Edited by Dynamic Dave on 02/04/2009 at 19:57

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Thu 2 Apr 2009 18:40
53 1.25 Emissions Light On (P0420) - topbloke
these should have a pre and a post cat sensor what is the exact description given for the p0420 code pls, Regards TB
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Wed 8 Apr 2009 17:20
53 1.25 Emissions Light On (P0420) - Venkman
All I know is the error code stated with reference to Bank 1 being below threshold. I have had 2 new O2 sensors fit (bank 1) and still the problem persists. The garage states it must be faulty cat fit, so the car is being fit with another new cat, under warranty, as we speak. Ill report back with any other problems.
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Wed 8 Apr 2009 17:39
53 1.25 Emissions Light On (P0420) - bell boy
Iwould consider the maf to be faulty and would try another if i was on it
however as i posted yesterday on a vw thread i have seen an aftermarket cat put the eml on after similar problems as yours,the only solution was an oe cat
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Wed 8 Apr 2009 20:52
53 1.25 Emissions Light On (P0420) - Venkman
Iwould consider the maf to be faulty and would try another if i was on
it
however as i posted yesterday on a vw thread i have seen an aftermarket cat
put the eml on after similar problems as yours the only solution was an oe
cat


Sorry to be a newbie, but what is, "maf" and, "oe"?

I have got my car back with a new cat fit, I still have what appears to be a spitting/misfire sound coming from the exhaust. The engine runs smoothly in idle, and the car sounds fine, but when applying some revs I get what sounds like a popping or spitting sound when sat inside the car. When stationary in neutral, the sound is more of a spitting sound. The emissions light is not on at present, Ill give it a few more miles!

Is this common for a new cat, is there a breaking in period where it mkes these sounds at higher revs?

Thanks
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