Dealing with the 'Preheat Fault' message [Stilo JTD]

Did the above procedure on mine, came up on multimeter as all 4 plugs working so put all back together. Warning went away after one start and have started several times since.
Must have been dodgy connection. Thanks for guide either way!

Argo, your a genius, great guide!

Having written this a little while ago I thought I would update it. Another plug has gone and I have the pre heat message all the time on statup. Followed the procedure again to find it was the third plug that had gone, the one on the black wire. Had a go at changing it but found it impossible. There is a metal fuel pipe in the way and the copper tube from the common rail crosses above the plug. I put everything back and will take it to a garage. I guess they have some special tools for this. I think plugs one, two and four could be done but three needs parts stripping down to access it which I wasnt confident to do and not sure of potential damage I may do. Leave it to the garage.

I've just done 1 and 2 on mine having found them both open circuit. I bought a socket set for the purpose via Ebay. It has deep glow plug/ spark plug type sockets with a UJ type drive and deep sockets which have a sprung clip in the end to retain the plugs and a 3/8th drive. It is a very fiddly job as the injector pipes are in the way amongst other things. You're not going to strip threads removing but you need to be careful when putting the new ones in as you don't want to start off cross threaded. I used a length of ally tubing which was a tight fit on the end of the plugs to hold them and start off the screwing back in. This way, you can hold them straight as the ally tubing is not fouled by anything so the plug is kept straight to it's hole. You can't do this with a socket as, even with a UJ, it would be extremely difficult to get it to start straight. It did take several starts of the engine to get the fault light to clear (about 8 I think).

Is it the same for Punto 1.9 jtd? Obviously everything isn't in the same place etc. I mean in general.

Hi thanks for this awsome thread
Done this today but i am very noob lol.
i bought a multimeter from homebase for £15 so obviously wasnt the best in the world but all the same worked fine.
on Pin 1 (YELLOW) = Cylinder 4 i got no reading wat so ever
on the other 3 i got the same reading .. 1

Im gona have a go at changing the plug my self tomorow. if i still get this preheat message could it be the actuall wire that we are testing with the multimeter? phillip from another thread has pointed this out to me.and if so has any one got a guide to changing it? will this be a hard job? thanks guys

SUCCESS! changed cylinder #4 glow plug , my first ever glow plug change and tbh was very very simple and took me about 20 mins and it solved my preheat problem 100 %
Thanks guys
i undone the 10mm fuel line nut to gain better acces to plug,unscrewed with long socket arm and removed old plug with long nosed plyers and installed new plug using the paper method mentioned a few posts back and it worked very well and poped the lead back on with the socket arm and reset computer with fiatecuscan.
Thanks guys

Excellent diagnotic guide! Did as you suggested and came up with the dreaded red wire, no.1 cylinder. I managed to change the plug with a bit of wriggling and all is now well, although I did manage to snap on of the plastic return pipes on top of the injector. Of course, no-one carries such a thing in stock and my nearest FIAT dealer is thirty miles away....but....Ford dealer managed to find a very similar item (slight angle on pipe is the only difference) and all is now well again.

This is definetly not a job for the faint hearted as there are so many expensive disasters waiting to happen. If in the slightest doubt about doing it...don't!

I might mention that the engine performance is much smoother now.

Thanks for the info, I would have been cluless without it.

Well done but highly recommend you change the other 3 too. Similar to spark plug changing. They may not be far behind in dying too.

I changed the wrong glow plug because Red(pin 4) was next to the flywheel on my car.

The diagnostic procedure on MJTD versions can be even simpler than this.

One only has to remove the engine cover and then measure the resistance between the exposed part of the plug itself (indicated by an arrow on the following image) and the engine (ground).
This way you also don't have to worry about replacing the wrong glow plug.
The wire colors on MJTD (at least on mine bought in 2004) are different than the ones in this guide (as shown in the upper right corner of the image) so the blue wire goes to the rightmost cylinder (4).

Changed htr plug #1 this morning after diagnosing it using the method in this guide - no probs - easy job - used a bike spoke to pull the connector off off - used 1/4 drive ratchet & long extn bar with deep 10mm socket, I secured the sock to the extn bar with some insulating tape to prevent it comming off, I also lined the inside of the socket with the same to make it a tight fit on the plug - make sure you use only a six sided socket - the 1/4 drive ensures you wont exert enough torque to break anything. I have the other four plugs but decided not to change them - I found this guide extemely helpful....Many thanx

N 1 on connector, yellow 153
others are 000-open circuits

so Number 1 is out?
and I think thats the most right one which is illustrated above on robbie-rocket-s post?

I have changed these myself before but now have one that is totaly siezed in. Three different garages have had a go but say they are afraid to try too much as it may snap and I should just live with three. I was wondering if I let the engine run to heat up and expand the metal will it help? Any other suggestions?

Even if it did shear off, you wouldn't be any worse off - and a good garage should be able to drill it out (albeit expensive of course).

My #2 plug failed recently so asked my usual garage to replace it but unfortunately it turned into a complete disaster. The thread stripped on the way out which instantly made a perfectly serviceable car unusable

This is why it can be madness to attempt to change plugs which are functioning OK (especially so on an old engine)