My neighbour has a 2013 Fiesta 1.25 with 20k on the clock & just had it's 2nd service @ Ford - no issues.

He's fanatical about servicing & as Ford don't change the air filter or spark plugs at this interval, he changed the air filter easily, but when he changed the original FoMoCo plugs ( made by Bosch ), & replaced them with NGK's the engine ran like a dog & the EML illuminated, he immediately turned the engine off, extracted all the new plugs & found two of them were sooted up in less than one minutes use.

He put the originals back in & the car runs perfectly & the EML is extinguished.

I have checked the NGK part number & they are the correct plugs for the car.

Does anyone know why this should be please ?

Thank you in advance

Some cars simply just dislike differently branded spark plugs. Have you checked the gapping of the new plugs?

Yes Kieran, the gap is correct

I should add that all the original FoMoCo ( Bosch ) plugs had a nice even tan colour - so no evidence of any issues, so it seems odd that just two of the NGK's were dry fouled ?

Where the HT leads definately connected properly and securely?

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Yes, triple checked as he says & I witnessed, & there were no issues when the original spark plugs were reinstalled - I find it hard to believe that NGK's aren't compatible with this engine, or that 2 out of 4 NGK plugs are faulty from new ?

Did you try the problamatic in different cylinders?

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I don't think he did that, I will ask him later.

What would doing that prove or disprove though Kieran ?

Wether it's the plugs themselves or something else along the line

I know it solved itself when you put the old plugs back in, but is it not worth checking for the sake of 10 minutes?

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Oh , , I agree with you totally !

Anything is worth trying, i'll suggest this to him later as both he & I find this an extremely odd problem

Maybe other 2013 Fiesta MK7.5 owners with the same 1.25 82ps / bhp engine will know too hopefully :)

It's a common enough car / engine

Were they the correct plugs? Some plugs have a R designation for ignition suppression and some electronic systems don't like them.

They are NGK TR5B-13's

I guess the R stands for resistor ?

These are listed as being correct for the 1.25 engine ?

I believe the R does indeed stand for resistor

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The originals are BOSCH HR7 MEV

I'm guessing the R here is also resistor ?

FoMoCo number is CYFS 12VN4 & they are actually made by Bosch - HR7 MEV

Correct plug, maybe duff ones, swap them around as above and see what happens.

Hi the same happened to mine rang ford help line and told not to use NGk plugs so I will not be using them again

Hope you get it sorted out

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Hard to believe that the No1 spark plug manufacturer in the world can't make a plug for the humble Fiesta :(

I'll tell my friend to try the swap method & if that fails he needs Bosch or FoMoCo plugs

Thanx Kieran & Diesel Pig & John & all :)

It is hard to believe but it right I just go to quick co in Trafford park ford parts

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I believe you John - it's a weird issue so it must be the plugs & if that's what Fraud say - then so be it

Thanx once again :)

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Had a big service on mine and told them to fit all ( plugs,all filters )

What are these FoMoCo plugs as i always check things after a service, i have these.

Runs smooth and all that

FoMoCo = Ford Motor Company

The FoMoCo plugs in the affected Fiesta are actually made by Bosch

The FoMocCo ( Bosch ) plugs are fine - the issue is with the NGK's

The engine in the affected Fiesta is a 1.25 82ps / bhp

I'm not sure if the same would happen in the 1.6. Fiesta engine ?

The NGK plugs have been returned to the supplier & a full refund issued & Bosch plugs are now in the car & it runs like a dream.

Sorted. :)

Cheers that cleared that up :)