Fiat 500 Misfire - Coil Pack Testing and ECU Explained

Fiat 500 and Punto engine management ECU malfunctions are common causes of power loss and intermittent to permanent misfire.
When performing diagnostic checks, you will find one or more cylinder/ignition coil fault codes stored in your engine management ECU.
These issues are often caused by a faulty coil pack on the vehicle, so Tim’s going to show you how to test for coil pack misfire issues…
Common Failure symptoms:
• Loss of power
• Misfire
• Engine management light
Common fault codes:
• P0300 - Random Cylinder Misfire Detected
• P0301 - Cylinder 1 Misfire Detected / Ignition Failure
• P0302 - Cylinder 2 Misfire Detected / Ignition Failure
• P0303 - Cylinder 3 Misfire Detected / Ignition Failure
• P0304 - Cylinder 4 Misfire Detected / Ignition Failure
• P0351 - Ignition Coil A Primary/Secondary Circuit Malfunction
• P0352 - Ignition Coil B Primary/Secondary Circuit Malfunction
• P0353 - Ignition Coil C Primary/Secondary Circuit Malfunction
• P0354 - Ignition Coil D Primary/Secondary Circuit Malfunction
Affected Vehicles:
• Fiat 500 (2007 - 2019)
• Fiat Punto (2012 - 2018)
www.ecutesting.com/common-fau...

[@HerbiesFilms]

That animation is giving me goosebumps, like button thoroughly SMASHED

[@boudewijn2648]

Nice video & info, thanks a lot!

[@g.w.r9707]

My fiat 500L misfires but only when its cold on start up it jerks when accelerating, once its warmed up after a few minutes it's fine, would the coil pack be a likely suspect ?

[@jas328sport47]

My 2014 fiat 500 runs perfectly when starting from cold until you stop it and restart it then it won’t run properly. It sounds as if it firing on 2 cylinders and the throttle butterfly is dancing around and it will not rev when pressing the pedal. If you keep trying then eventually it will start to rev to 4K and then eventually will start to rev fully again and then runs faultlessly until you stop and try to restart again. Does this sound like an ecu problem or not. I don’t want to fire the parts cannon at it and a scan at my local mechanics showed no faults.

[@cluger2010]

Great demonstration. Currently am working on the Fiat Punto NO crank and NO start checked battery, startor found all good scan tool is not detecting Engine Ecu what could be the Issue.

[@Ecutestinglimited]

Hi, we are glad you enjoyed the video. If your scan tool cannot detect the ECU, then we would recommend checking the basics first, i.e. the power supply and ground connections to the ECU, and all relevant fuses. We have gone through these steps in a video here: kzbin.info/www/bejne/j2TEoHdrd7Krh9k. Cheers

[@jerrycruz6442]

Hello i have a 2009 fiat 500 and i just put a new engine in it and it wont start.. I have used the computer to diagnose the problem and it telling me that my ECU isn't getting any power and i checked al the wires, al the sensors and al the fuses and everything seems to be working but it stil wont start.

[@JohnCrebo]

Great video! One question- I’m testing the coil pack as per 1:07 (pin 1 and pins 2-5), and getting no readout. Pin 6 and pins 2-5, all give a readout of 0.8. Am I doing something wrong or is my pack knackered? The engine has been starting, but has been misfiring. No codes have been thrown up though. 2nd time with this issue- first time I changed the plugs and the problem stopped for 6months

[@Ecutestinglimited]

Hi, are you testing a Fiat 500 coil pack or one from another vehicle? Thanks

[@JohnCrebo]

Hi, yes it’s a 2004 fiat 500 coil pack. Just spoke to the dealer, and they tried to claim that a fault in the coil pack will prevent starting at all, and probably wouldn’t damage the ecu.. I think they’re trying to get me to take the car to them and pay a £190 diagnostic fee 🤦🏻‍♂️ Do you think I’m measuring the coil pack wrong? Having said that, I’ve reconnected it back up and not had an issue. It’s frying my head to be honest lol 😂

[@JohnCrebo]

@@Ecutestinglimited .

[@Ecutestinglimited]

@@JohnCrebo We would actually agree with the dealer here, if you weren't getting an initial reading from pins 2-5 against pin 1 then the car shouldn't start, so it must be something with method you're using to measure the coil pack. Are you testing the voltages at the coil pack plug and not the loom end?

[@JohnCrebo]

@@Ecutestinglimited I had my meter set to 600 ohms (the lowest setting), and recorded ‘- - - -‘ across pins 2-5 against pin 1. And the same method with pins 2-5 against pin 6, gave me 0.8ohms. This was when remover from the vehicle. Maybe error on my part in touching terminals- who knows. This evening however, I have systematically pulled every fuse, and replaced, pulled and replaced the leads, and the lion from the ecu and replaced. The car does feel like it had more power- so I think potentially something must have been loose and created a weak spark? The ODO on the dash is still flashing, and there is still no Blue & Me hands free system so I hope there hasn’t been any damage to the boards Hoping this has solved the issue and not masked a deeper problem!! Thanks again- your video has been a great help and you’ve been great in getting back.

[@TheShed929]

Have a 2019 Abarth which misfires when cold until it warms up then runs ok. Have checked pretty much everything apart from ecu, what's your turnaround for checking the ecu. Thanks

[@Ecutestinglimited]

Hi. Please visit our website www.ecutesting.com and search for your ECU part number for the most up to date pricing and turnaround times. If you cannot see your part number on our website, please email it to [e-mail], along with the details of your vehicle's make and model, symptoms and fault information, as well as any diagnostics you have already carried out, and they will assist you further. Thanks.

[@LynnLight]

This is exactly what has happened to my 2015 Fiat 500 POP, but my mechanic has said nothing about the ECU being no good, but i have a huge feeling that it is all shorted out. I say this because of what I heard in the video, and also because when I started the a few days ago, it started up so rough that I noticed the check engine light flashing, so I shut the car off and had a tow truck take tow my car to the mechanic's shop. They have told me that two of the coils are showing that they need to be replaced, but that they are going to replace all four of them. I would think that I also need to have the ECU rebuilt. Chances are with the coils being bad it means the ECU got burned up Right? I want it rebuilt after reading how a brand new one won't last more than a year due to a faulty design and I would rather get a long standing warantee too.

[@Ecutestinglimited]

Hi. Generally you are correct that when one or more of the coils are faulty, they can damage the ECU. If you would like to get your unit tested to see if it requires a re-build, then please contact our technical support team via email at [e-mail], with the following details: Your make and model of vehicle, the details of your fault as described above, and any further relevant technical information (such as previous repairs carried out on the vehicle). Thanks

[@bartgroenewegen6974]

Hi guys, great video. i tried to measure the first one from 1-2-5. dindt get anything. the other way around., 2nd measuring from 6 to 2 it gives me 0.04 - 0.06 max. can that also be the coil being broken for the fiat 500 1.2? thx

[@Ecutestinglimited]

Hi. From what you have described it sounds like your coil pack is faulty. We would recommend trying to replace this and then re-test to confirm.

[@onlyme8870]

I live in US i did coils plugs injectors filters carbon test but didn't know about ECU. As I still get the shaky car and cyl 2 misfire still. I have a 2015 pop 500 1.4l non turbo

[@Ecutestinglimited]

Hi. If you have ruled out everything you mentioned in your comment, then it is likely that your ECU has been internally damaged and failed. If you would like to send it in to us for a re-build, we do offer a worldwide service so you can simply fill in our online test form at ecutesting.com. If you have any other questions please contact our technical support team at [e-mail]. Cheers

[@AlvinBrinson]

One difference is the US cars only come with 1.4 multiair, which has individual per cylinder coils. So there is no possibility of a shorted coilpack burning the ECU like happened here. That said, there are some other things that can damage the ECU.

[@Gdljal24]

hello I have a Fiat Doblo in my shop right now and no matter how many times I replace the coilpack on cylinder #3 it keeps burning them it even melts I trace the wires and they dont touch ground at all what Im suspecting is the ECU its fried

[@LynnLight]

What I got from watching the video about the coils going bad on the 2015 Fiat 500 POP is that when two coils go, your ECU is fried. I also got that you should send the ECU unit to be rebuilt because it you just buy a manufacturer's ECU they are all faulty and won't work for more than a year. It you have your ECU rebuilt by ECUtesting in Britain they rebuild it and give you a lifetime warranty and you won't have repeated problems.

[@lunayogini21]

Great Video. I'm learning much about my 2015 Fiat 500. I've got 99k on it and the spark plugs and coils have never been changed It is reading PO300 01/o3 freeze frame, 02/03 pending 03/03 permanent I'm wondering should I start with spark plugs and coil change and also have coil pack tested? Before assuming the ECU is damaged?

[@Ecutestinglimited]

Hi. If you are getting any secondary fault codes we would recommend dealing with those first (e.g crankshaft sensor codes), but if you are only experiencing misfire codes then yes we would recommend ruling out spark plugs and coils first before condemning the ECU. If you do believe your ECU is faulty then please feel free to send your unit into us for testing at www.ecutesting.com.

[@lunayogini21]

@@Ecutestinglimited Thank you so much for your response. I have a basic OBD2 scanner. I'm assuming the best course of action is to have it towed to a mechanic who can do a more thorough diagnostic. AS you have mentioned it could be ECU malfunction. To avoid unnecessary cost AND given on the OBD2 scanner it showed PC300 o3/03 permanent is it likely that it is the ECU if no other readings show problem? I live in California and don't want have unnecessary repairs. Can a mechanic who works on European cars have the diagnostic equipment to determine if the it's the coil pack, the ECU or both? Thank you so much for your help.

[@Ecutestinglimited]

Hi. The P0300 being permanent doesn't mean it is more likely to be an ECU fault, as badly worn spark plugs/faulty coils and other faults can cause a permanent code to be set. We would recommend contacting a garage who has diagnostic equipment and experience specifically for Fiat vehicles to be on the safe side.

[@lunayogini21]

@@Ecutestinglimited Thank you so much for your guidance. I have found a mechanic who is familiar with the Fiat 500.

[@lunayogini21]

@@Ecutestinglimited Good Day, the spark plugs have been changed. The shop is not specific for Fiats but has worked on Fiats. They have not changed the coils to the spark plugs yet. He said that the code is reading Po300 not indicating there is a problem with the coils. Do you think the coils should be changed to see if that will remedy the misfire before we go further ?

[@georgescutt6784]

Hi daughter fiat 500 turning over but not firing was told it has low compressing and was told it’s the head gasket? Does this sound abt right?

[@Ecutestinglimited]

Hi. If you have the vehicle diagnosed by a garage and they have identified the cause of the fault as low compression, then a blown gasket can be a cause of this. However there are other causes, so we would recommend getting the vehicle diagnosed by a garage if you haven't done so already. Cheers

[@georgescutt6784]

Many thanks 🙏

[@AlvinBrinson]

Did the car sit for a long time before having this issue? If it's a multiair, they have problems starting up after sitting for extended times due to oil bleeding out of the multiair unit.

[@sa3dtantan918]

شكرا

[@aarixk2620]

Does this apply with a 2013 dart 1.4

[@Ecutestinglimited]

Hi. The basic principle will be the same, however this video is specifically for Fiat 500's.

[@AlvinBrinson]

Except for the coil pack short, as there's no single coil pack on the 1.4 multiair but rather individual coilpacks.

[@bensontemu9356]

Good

[@mattrobinson6475]

Just adding if you do need to change the plugs make absolutely sure you replace them with the original NGK ones.

[@brahimmeguireche8906]

👍

[@dancanseealiar1]

I dont understand why 0.0 ohm between 5 and 6 is faulty

[@aligoode6061]

Because the other pins read O.L(meaning not connected) so 0 ohms means there is a connection with no resistance i.e a short between the positive on one of the coils and the common ground. as far as i understand it.