Fiat 500 ECU fault causing misfire

Fiat 500 ECU fault

This Fiat 500 engine ECU will cause engine misfires across one or more cylinder after driving over 40mph/64kph. When the ECU becomes faulty the engine will be forced into limp mode, significantly reducing power and the engine waning light will flash.


When diagnosing this Fiat 500 misfire, fault codes will be found for misfire detection across multiple cylinders. You may be able to clear these faults by cycling the ignition off and on again, or via scan tools but the fault will return as soon as the vehicle gets back up to speed.


Main dealerships may seek to resolve this problem by purchasing an expensive replacement from manufacturer. However not only will this need coding at an extra expense and only come with a short one year warranty, but it will be prone to fail in the same manner. The manufacturing defect has not yet been rectified at factory level, meaning all replacements will fail at some point.


We offer test and rebuild of this Fiat 500 ECU, our in-house team will engineer-out the cause of these problems so that it will not fail again. We will rebuild within 3-5 working days and return you ECU with an unlimited mile lifetime warranty.



*This problem will also affect the Ford KA Mk II 2008 – 2016 as it shares the Fiat 500 automobile platform


Common Failure symptoms:

  • Misfire
  • Limp mode
  • Flashing engine warning light


Common fault codes:

  • P0301 – Cylinder 1 Misfire Detected
  • P0302 – Cylinder 2 Misfire Detected
  • P0303 – Cylinder 3 Misfire Detected
  • P0304 – Cylinder 4 Misfire Detected
  • P0300 – Random / Multiple Cylinder Misfire Detected


(*Can’t find your part number? Click to check your model here: 500, Panda and Punto)


Test and rebuild:

Each engine management ECU is rigorously tested on our bespoke test rigs both before and after rebuild to ensure that it will meet and exceed manufacturer standards and to ensure the ECU will not fail again. During the rebuild process we only use higher than standard rated components.



We keep all the original coding so that you can just plug in and go once you receive the ECU back from us.



Franchise dealerships and specialists have been benefiting from our rebuild services for many years and our work defect rate is lower than 0.49% on all rebuilds, so you can be assured of our very high standard of work.



Lifetime unlimited mileage*


How do I get my unit rebuilt?

To pay for the rebuild select your part number and click: Get yours rebuilt

Print the payment/booking confirmation email.

Package the engine ECU inside a sturdy box with plenty of packaging material (make sure you include your confirmation email in the box).

Send us your package by tracked courier (the shipping instructions are on the confirmation email).

Once received we will test, rebuild and return your Fiat 500 ECU with an unlimited mileage lifetime warranty. (if your unit turns out not to be faulty then we will refund your payment less a small testing fee and return shipping)


What if I don’t want to pay up front?

This is not a problem, if you prefer this option then follow the following steps:

Fill in and submit this test form.

Print the booking confirmation email.

Package the engine management ECU inside a sturdy box with plenty of packaging material (make sure you include your confirmation email in the box).

Send us your package by tracked courier (the shipping instructions are on the confirmation email).

Once received, we will test your ECU and call you to advise on the outcome of testing, if your unit is faulty and you choose to go ahead with the rebuild then we will take payment over the phone using a debit/credit card.

We will then rebuild your engine ECU and return it to you with an unlimited mileage warranty.

If you require further information regarding this Fiat 500 engine ECU then please contact us.

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Comments on "Fiat 500 ECU fault causing misfire"
David OHalloran says: 1/1/2020 10:11:07 AM
do you service internationally? I am in Australia and have a misfire with my Fiat 500 Twinair. Two mechanics have failed to fix the problem. Can you assist me? Thanks David
ECU Admin says: 2/1/2020 2:19:16 PM
Hi David, we certainly do offer international service. For prices and shipping information please select your part number above.
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