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This guide provides instructions on how to diagnose the Fiat check engine light yourself.

Table of Contents

Fiat Check Engine Light (CEL) may come on and stay on for multiple reasons.

In newer Fiat models, such as the late-model Fiat 500, you will note the "HAVE YOUR ENGINE CHECKED" message on the dashboard.

The problem could be something as simple as a loose gas cap (fault code P0456) or an indication of another problem, such as a turbo boost issue, engine malfunction or misfire, and even a transmission problem.


The light itself does not provide much information other than warn you to get the car diagnosed. 

It is impossible to know why your Fiat check engine light is on without reading the codes. You will learn how to read codes in the next section. 


fiat check engine light

A list of symptoms you may notice when your Fiat check engine light comes on.

  • poor throttle response,
  • engine jerking when changing gears,
  • engine overheating
  • "high coolant temp, turn the engine off" warning,
  • engine stalls at idle, or car is difficult to start.

The symptoms of Fiat check engine light vary. Sometimes you may not notice any performance issues at all.

If you don't notice any performance issues, you can continue to drive your Fiat but get it diagnosed as soon as possible.

Why is my Fiat check engine light (CEL) on? 

fiat gas cap triggers check engine light

The most common problems triggering Fiat check engine light are worn spark plugs or a loose gas cap. 

Other issues can trigger the check engine light on a Fiat, such as:

  • Poor fuel: Low-quality gasoline can trigger the CEL on Fiat vehicles
  • Turbo problem: Under boost pressure
  • Thermostat: Engine overheats or takes too long to reach operating temperature
  • Oxygen sensor: Increases emissions, a decrease in fuel economy.
  • Mass airflow sensor: Often results in multiple codes and poor throttle response
  • Spark plugs: If one fails, it will cause engine misfire and engine shaking
  • EVAP: The EVAP emissions canister can fail, triggering CEL and codes such as P0499.
  • PCM: Failure changing spark plugs and wire harness does not fix the CEL. PCM replacement may be required.

Note that many more possible problems and hundreds of Diagnostic Trouble Codes (DTC) can trigger the CEL on your Fiat.

Without diagnosing the vehicle, it is difficult to know what the problem is in your particular case.

How to Reset Fiat Check Engine Light

The following instructions work on Fiat vehicles manufactured from 1996 to the present. An OBD-II scanner is required to read the codes. 

  1. Turn on Ignition. All your dashboard lights should be on. Do not start the engine.turn fiat ignition on


  2. Plugin your scanner into the OBD II port under the dashboard. There is only one port like this. Sometimes it has a small cover, so you may not notice it easily. It may be hidden under the dashboard, which will require you to look carefully under the port to diagnose check engine light


  3. Allow the scanner to communicate with your Fiat and detect the correct protocol. fiat check engine scanner
  4. Press read codes on your OBDII scanner or phone app to retrieve the codes.
  5. Fix the problem that triggered the codes you retrieved in step 4; come back to the main menu and select Clear Fault Codes. 

These instructions will allow you to check engine codes on Fiat models such as Fiat 500, 500x, Abarth, Panda, Fremont, Viaggio, Ottimo, Ducato, Dublo, Tipo, Toro, Mobi, Argo, Punto, Panda, Croma, Sedici, Bravo, etc.

Can a loose gas cap trigger the check engine light? 


fiat loose gas cap triggered check engine light

Yes. If you scan your Fiat and the code that you get a code for EVAP leak, make sure you tighten the gas cap until you hear two clicks.

You can also use an OBD-II scanner and clear the code once you tighten the gas cap. If the CEL comes back, replace the gas cap.

If the CEL comes back on again, with a code for a small EVAP system leak, have a mechanic, or your Fiat dealer would have to perform a smoke test to find the leak.

It is strongly recommended to write down the code and research the problem. Many owners get a code and start replacing parts based on the code alone. Later they find out that the replaced part didn't fix the problem.

Don't start replacing parts without researching the code first. There is more than one problem that can trigger one code.

Fiat Check Engine Light Flashing On and Off

fiat check engine light flashing

If your Fiat check engine light is flashing, it means that the onboard diagnostics system (OBD) has detected engine misfire. In other words, one or more of the cylinders is not working properly.

It is not recommended to drive your Fiat if the check engine light is flashing. Driving your Fiat with CEL flashing can cause more damage to the engine and catalytic converter.

As long as your Fiat check engine light is NOT flashing, it is usually safe to drive.

If you decide to drive your Fiat when the CEL stays on, you should carefully monitor dashboard warning lights and the engine temperature.

Do not drive if the engine is shaking or hesitates when pressing the gas.