Today’s cars are way more than simply a chassis with an engine and four wheels. Scores of processors are required to keep your vehicle’s systems working efficiently and safely. Many of them require ongoing, over-the-air firmware (software) updates. Learn how these OTA updates work and why they are so important.

If your car was built in the last few years, it’s likely to have dozens of computer chips (CPUs and GPUs) perhaps even more than a hundred if it’s a premium or EV model. These processors manage everything from your engine to your airbags and infotainment system.

But in order to function effectively, these processors need firmware - a kind of software. Some of this firmware will need to be updated periodically.

This is where “over-the-air” (OTA) car software updates come in.

What does OTA mean?

As the name suggests, over-the-air updates are wireless software updates delivered “over the air” to a vehicle via:

• Wi-Fi
• Cellular (4G/5G)
• Occasionally satellite
  

They work in a similar way to smartphone updates but with added security layers as today’s cars involve safety-critical systems.

How OTA Updates Work

Your car has a built-in telematics unit

This unit basically consists of a modem (for data connection), antenna and a small computer. It communicates with secure servers operated by the manufacturer of your car.

Your carmaker prepares the software package

The car software update might target one or several of your car’s systems, such as:

• Infotainment (maps, apps, interface)
• Battery management
• Driver-assistance systems
• Charging logic
• Powertrain control
• Safety modules
• Navigation or camera calibration
  

Critical systems use encrypted, signed firmware so your car only accepts authentic updates. While there have been no publicly verified cases where vehicle firmware updates have been made by malevolent actors (criminals, enemies of the state etc.) such an attack is theoretically possible, and therefore must be guarded against.

Your vehicle downloads the update

This might happen:

• While parked and connected to your home Wi-Fi
  
• Over mobile data while driving (download only; installation usually waits until vehicle is parked)

Note: This ‘mobile data’ is provided by the car maker.

The car verifies the update

Before installation is allowed to begin, the system checks:

• Encryption keys
• Integrity (making sure there is no corruption)
• Compatibility with existing systems
  

If any of these checks fail, the car software update is rejected.

Installation takes place safely and successfully

Infotainment updates can usually be installed while the car is running. But critical system updates (brakes, steering, Advanced Driver Assistance Systems/ADAS, etc.) usually require the vehicle to be parked with the ignition off. The battery level must also be stable.

Some modern cars use redundant systems, meaning that one module can be updated while the other keeps the car functional. Such systems mean that updates are carried out with minimal to zero impact on the car’s usability.

Security measures

As mentioned, OTA updates require strict security because any breach could be dangerous. Protection includes:

• End-to-end encryption
• Digital signatures
• Hardware security modules (HSMs) inside ECUs
• Secure boot (vehicle won’t run unverified firmware)
• Rollback options if an update fails (i.e., the system can revert to the previous software version if necessary)
  

Why getting the latest software updates matters

Issues get sorted out instantly

Car companies can patch bugs remotely - sometimes overnight. This saves you the time and inconvenience of having to take your vehicle to the dealership to get a software update.

Updates may improve safety

Updates can enhance things like emergency braking, lane-keeping accuracy, crash-avoidance algorithms, and camera/radar processing.

Getting the latest software updates means your car can become safer over time, and is not simply left as it was when it rolled out of the factory.

New features may be added

Manufacturers might roll out:

• New driving modes
• Better range estimation
• Enhanced navigation
• Voice assistants
• Games or apps
• Charging improvements
  

Some even enable paid features (e.g., heated seats, ADAS add-ons).

Performance boosts (for electric vehicles)

As regards EVs, updates might boost performance in various ways, such as:

• Faster charging rates
• More efficient battery use
• Added horsepower or torque
• Smoother acceleration
  

Lower ownership costs

OTA should reduce:

• Workshop visits
• Diagnostic labour
• Recall overhead
• Customer inconvenience
  

Vehicle lifespan may be extended

Since hardware evolves slower than software, OTA helps cars stay efficient for longer.

Updates are critical for autonomous driving systems

For vehicles with any sort of autonomous/self-driving functionality, updates are absolutely critical. These might impact things like:

• Constantly updated maps
• Improved AI models
• Bug fixes
• Safety patches
  

Without OTA, autonomous vehicles would be impossible to maintain safely. As self-driving technology advances, the safe delivery of such updates will remain paramount.

The different types of OTA updates

Soft or “infotainment-focused” OTA

These updates might focus on maps, apps, improvements in the user interface, and any necessary connectivity fixes.

Full-vehicle / Firmware-over-the-air (FOTA)

Full-vehicle or firmware updates are critical and are usually carried out only when the vehicle is parked, with the ignition off. Such updates impact things like the powertrain, battery, ADAS sensors, steering and braking systems, and airbags and safety modules.

Only a few carmakers currently support large-scale FOTA (Tesla was first, but others are catching up).

Do I have any control over updates? Can I refuse the update?

You cannot refuse critical safety updates, such as those relating to braking, airbag systems, stability control, ADAS/autopilot safety logic, or cybersecurity fixes.

However, you may be able to postpone some updates, or refuse non-critical updates (such as alterations to the user interface).

But in short, if the firmware/software are critical to the safe operation of your car, they will be downloaded and installed automatically, without needing your approval.

Will my car stop working if an update fails?

It’s very unlikely that your car would stop working if an over-the-air update fails. This is because modern vehicles are designed specifically to avoid being “bricked” (prevented from operating) by a bad or incomplete OTA update.

Today’s cars use “dual-bank” or “A/B” firmware systems which store two copies of the critical software:

• Slot A: current working version
• Slot B: the new update

If the new car software update fails, your car would automatically revert to the old version, or simply wouldn’t switch over until the update is complete and fully verified.

Additionally, critical systems are updated separately and very cautiously.

In conclusion

OTA updates let your car evolve continuously. Problems are fixed, features are added, performance is boosted, and safety levels are maintained. All of this is done remotely.
 
In summary, over-the-air updates are critical for modern EVs, connected cars, and particularly for any autonomous driving systems.