2012-2019 Fiat 500 Key Fob Guide: The Truth About Programming Used Keys

Common Symptoms of a Failing Fiat 500 Key

When a Fiat 500 key starts to fail, the symptoms can be confusing. They range from simple annoyances to leaving you stranded. Understanding the signs can help you pinpoint the problem quickly.

1. Remote Buttons Stop Working or Have Poor Range

This is the most common failure. You might find you have to be standing right next to the car for the lock or unlock buttons to work. Eventually, they may stop responding altogether. This almost always points to a weak or dead CR2032 battery inside the key fob.

2. Car Won't Start (Immobilizer Failure)

A more serious symptom is when the car refuses to start. You can turn the key, the dashboard lights up, and the engine cranks, but it never fires up. This often means the car's Body Control Module (BCM) is not recognizing the transponder chip inside the key. The chip itself does not require battery power to function, so this indicates a deeper electronic failure within the key fob.

3. "Key Not Detected" or "Break-in Attempt" Messages

Your dashboard may display a specific warning like "Key Not Detected" or "Fiat Code System Failure". In some cases, a key that has lost its synchronization can even trigger a false "break in attempt detected" message on the instrument cluster.

4. Intermittent Functionality

The key might work perfectly one moment and fail the next. This can be caused by a failing battery, a loose connection on the key's internal circuit board, or even a problem with the car's central locking fuse. Some owners report that extreme temperatures, like leaving the key in a cold place, can temporarily cause issues.

Buying a Used 2012-2019 Fiat 500 Key: What You MUST Know

This is the most important section for anyone looking to save money by purchasing a used part. For this specific vehicle, buying a used key is full of pitfalls.

The Critical "Precoding" Problem

Replacing a Fiat key is a two-stage process: precoding and programming.

• Precoding: A brand new, 'virgin' transponder chip must be loaded with your specific car's secret security code. This is done by a dealer who looks up the code by VIN, or by a specialized locksmith who can extract the code from your car's BCM.
• Programming: This step simply authorizes the already precoded key to work with your car.

A used key is already precoded and locked to a different car, making it useless for the immobilizer function on your vehicle. Some very specialized locksmiths may offer a 'virginizing' service to wipe a used key, but this is not common. For most buyers, a used key is only good for its outer shell and buttons.

What to Do if Your Key Shell is Broken

If your key's electronics work fine but the plastic case is broken, you can buy a new or used key fob shell. You can then carefully transfer the internal circuit board and transponder chip from your old key into the new shell. This is the only recommended use for a typical 'used' Fiat 500 key.

Step-by-Step Diagnosis

1. Replace the Battery: The first, easiest, and cheapest step is to replace the CR2032 battery. This solves the vast majority of remote lock/unlock issues. A new battery costs only a few dollars.
2. Test Your Spare Key: If you have a second key, test it. If the spare key works perfectly, the problem is isolated to your primary key. If neither key works, the issue may be with the car's receiver module or a fuse.
3. Check Fuses: A blown fuse for the central locking system can make it seem like your key fob is dead. Check the vehicle's fuse box for any blown fuses related to door locks or the BCM.
4. Attempt a System Reset: Some owners have reported success by disconnecting the car's negative battery terminal for about 15 minutes. This can sometimes reset the car's electronic modules and restore communication with the key.

Replacement and Programming Guide

Due to the security requirements, replacing and programming a Fiat 500 key is not a simple DIY job. It requires special tools and information.

The general process is as follows:

1. Obtain a New Key: Purchase a new, un-programmed key from a dealer or a reputable aftermarket supplier. Ensure it is a 'virgin' key ready for precoding.
2. Cut the Blade: A locksmith or dealer will need to cut the physical key blade to match your car's locks.
3. Program the Key: This is the complex part. A technician uses a diagnostic tool (like MultiECUScan, AlfaOBD, or a professional locksmith's programmer) connected to the car's OBD-II port. They will enter the security PIN code and follow a specific procedure to program the new key—and any existing keys—to the car.
🎬 Watch a professional technician program a new Fiat 500 key.

Cost Comparison for a New Fiat 500 Key

Known Issues and Recalls

While there are no specific recalls for the key fob itself on the 2012-2019 Fiat 500, there are a few related service campaigns for the North American market that are good to be aware of.

• NHTSA Recall VB4 / 19V825000: Affects some 2012-2013 models with automatic transmissions. The shifter cable bushing can detach, meaning the gear selected by the driver may not match the actual gear the transmission is in. This could lead to a rollaway risk if Park is selected but not engaged.
• NHTSA Recall S34 / 16V421000: For 2012-2016 models with manual transmissions, the clutch diaphragm spring could fracture, causing an inability to shift gears.

These issues are not caused by the key, but a car that won't shift into gear could be misdiagnosed as a key-related starting problem.

Frequently Asked Questions (FAQ)