I am finding that I am having change the HT leads on my skoda fabia 61 plate on a yearly basis. 

I don't much mileage per year between 6-8k. Is this normal?

Any ideas? Is there is an issues that I maybe I'm missing as to why I am having to replace them so often. 

Seen other posts about lead melting and wire with the lead being affected - Sorted this issue a few years ago or thought I had but still finding that I am having to change them yearly. Can tell when they are going as cat becomes more 'jittery' .

 

Only had car 5 years and so far changed them every year I have had the car.

Welcome. 

Please give us a clue about which engine variant this is?

It's a 1.2 TSI

Why or what leads you to changing the laeds?

 

How often have you checked and replaced spark plugs?

 

Was No.3 lead ever changed for the one with armour? 

Edited 21 July, 20214 yr by e-Roottoot

Spark plugs were replaced a couple of years ago along with the HT leads and yet leads had to be replaced again last year.

Didn't do the work myself so unsure if no 3 lead was changed with armour one. But they leads were purchased from a retail motor shop so I guess probably not.

Also further info - car broke down on motorway last year - RAC guy changed the ignition coil as they thought this was the issue but this made no difference.  On this occasion it was the HT leads that needed replacing ( and when i checked how long it had been since they were last change it was roughly same time the previous year)

Its highly unlikely leads go faulty in such a short time/mileage scale. Genuine Skoda replacement have a 2 year warranty. Many aftermarket have the same or longer warranty.

 

Who is diagnosing the faulty leads, how and what are the symptoms?

 

Presumably its a cbzb engine 1.2tsi 105ps.

 

Plugs need changing at 40,000 miles with iridium fine tip (NGK if you have leads with 9k resistance or Bosch if the leads are copper core or low resistance). 

 

Two types of leads are available, the original style are unsheathed and have a resistance of 9k ohms. Later ones have corrugated trunking protecting them (called marten protection) these are better are protecting the leads from heat damage from the exhaust/turbo. You should make sure leads are clipped away from the heat shield.

 

Coils can and do break down, usually when the leads go open circuit or your plugs are too worn out.

 

Unprotected style no.3 lead is the usual lead to fail, as it rests on the heat shield.

 

My guess is someone incorrectly thinks leads are faulty because they don't buzz out with a continuity tester. Or perhaps some incorrect cheap non fine tip plugs are fitted.

 

Or something else is causing misfires or rough running, unrelated to ignition.

 

 

It might be you are the goose that lays the golden egg for them.

 

Look at the lead for cylinder 3 and see if it is different.

That could of been or should have been replaced while your car was in warranty if you had Main Dealership Servicing.

 

I have not had anything to do with them but @xmanmight be able to give you more info on this.

 

EDIT, 

sorry was typing as he posted.

Edited 21 July, 20214 yr by e-Roottoot

Thanks  e-Roottoot and xman. This has definitely given me something to work with. Last set of leads I had installed were Bosch ones and they were only put in December 2020, which made me start looking at forums etc to see how common an issue it is and how long they should be lasting.

It's now making me think it could be something else, which is impacting the leads as car definitely runs better once leads have been changed.  

Looks like I new to find a new garage though now to take my car too as well  

I suggest you check you have the correct iridium spark plugs fitted and whether they are not worn out (maybe they didn't change one/all because it was difficult). While they are out check the tip to connection resistance NGK = 1kohm BOSCH = 6kohm (approx) 

 

NGK IZFR6P7 (97153) 

or 

BOSCH 0242240665 [ FR6HI332 ]

 

You might want to consider if the garage you use can be trusted.

As I said earlier, Skoda parts come with a 2 year warranty, if they fit them it will be a 2 year parts and labour warranty.

 

We have had 2x 1.2tsi engined cars with a total of 270,000 miles and 15 years service. The 2011 car had a no.3 lead fail (which took out the coil pack) at 50,000 miles 3.5 years. With the new lead style fitted there have been no further failures still going strong at 150,000 miles / 10 years

 

Old style leads

 

 

 

New style leads

 

 

Also worth mentioning is the spark plug boot connection is extremely tight with a close fitting rubber seal. A light smear of special grease is supposed to be applied to stop the rubber sticking/bonding to the ceramic insulator. It is imperative that an appropriate tool is used to pull the metal boot off the plug. If someone tries to disconnect the lead off the spark plug by pulling on the lead, they will invariably break the lead's core. So a clumsy or ignorant mechanic could easily damage a lead.

 

 

Edited 21 July, 20214 yr by xman

Reviving this old topic to ask: this shouldn't happen to the sheathed lead, even no 3, in under two years (about 20k miles) should it..?

Not touching shield but very close, and that's routed and clipped correctly, as far as I can tell (ie there's nothing else available to hold or support the lead to be further away).

CBZB 85hp engine, 2011.

try to undo the leads and re-clipping them pulling them towards the firewall instaed of leaving them whit the possibilty to move closer to the turbo heat shield.

however i suggest to replace it, pesonally i wouldn't trust it

Edited 13 April13 Apr by Jack25