P0606 is a generic OBD II code. Which means that it has the same meaning for the Fiat 500 that it would for any other vehicle. If your 500 has P0606 it’s highly likely that the ECM/PCM (engine or powertrain control module, they mean the same thing) has failed.
The PCM regularly performs a self diagnosis cycle. When it fails this test P0606 will be stored in it’s memory and you’ll get the P0606 trouble code.
P0606 Symptoms: Fiat 500
Here are the most common symptoms of P0606 in your 500. It’s highly unlikely that the check engine light will be the only symptom.
- Service Engine Soon Light- This is the most common symptom associated with P0606 in your 500.
- Misfiring- When driving the vehicle may misfire as though it has normal ignition problems. The PCM’s job is to manage the engine timing and interpret the data for optimal combustion. When your 500 has P0606, the PCM may no longer be able to do this job effectively. This may also lead to a decrease in fuel economy.
- ABS and Traction Control Lights- The ABS and traction system lights may illuminate as well.
- Shifting Problems- Your 500 may not be able to properly shift, or shift at the right time, when P0606 is present.
One of the most common things that happens when this code is present is the average person will start trying to find what is causing a misfire by inspecting and replacing ignition system parts, when really it’s the PCM that is not properly communicating with the engine.
P0606 Causes: Fiat 500
Most of the time, P0606 is going to be caused by a defective PCM. The fix will involve either getting a new unit or having the dealership reflash it for you. We recommend having a professional do this. There’s a lot that goes into calibrating a PCM.
It is very unlikely that your 500’s PCM randomly failed. It is more likely that some external factor caused it to go bad. Typically a wiring issue in the harness coming to or from the PCM can cause it to go fail. Replacing the PCM without testing for shorts, bad grounds, or defective CAN bus communication may lead to another failure.
Conclusion: P0606 500
The mission of this website has always been to help the person doing the job themselves get it done. On this one though, we recommend calling in some expert help. If there is anything that you would like to add, please leave a comment below. Good luck fixing your Fiat 500!