Modern vehicles are packed with dozens of electronic control units (ECUs) alongside other modules. This includes powertrain, infotainment, ADAS, body control modules, and more. One of the challenges for OEMs and Tier 1 suppliers is the fact that any module, at any time, at any stage of production, may suddenly require a software update. Known as a reflash, this update may be to fix bugs, roll out new features, or ensure compliance with regulatory changes.  

Traditionally, these reflashes are done one at a time, in sequence. And while sequential reflashing works well, the problem is that it can be slow in situations where OEMs and suppliers need things to happen quickly. 

That’s where parallel reflashing comes in. By updating multiple modules at once, parallel reflashing techniques can significantly reduce the time and resources required to complete software campaigns. 

What is parallel reflashing? 

Parallel reflashing involves performing software updates on multiple ECUs or modules simultaneously, rather than sequentially. Reflashing can happen on modules inside the vehicle, on the assembly line, or in a bench setup with loose modules. 

This approach is made possible by dedicated multi-channel hardware, such as the Movimento Puma 5, which can handle several reflashing tasks in parallel.   

Technicians can connect reflash to the OBD port, custom harnesses, or directly to module connectors during bench reflashing.  

Modules that are good candidates for parallel reflashing include door and seat controllers, radar and camera units, infotainment systems, and other subsystem ECUs. 

Communication between reflash hardware and the modules typically runs over CAN or Ethernet, with Ethernet offering higher bandwidth and reduced risk of bottlenecks.  

Parallel reflash considerations 

The number of modules you can reflash in parallel depends on several factors: the availability of communication channels, the vehicle’s network architecture, and any software or power dependencies between modules. 

Some modules can’t be reflashed unless others are updated first. For example, in some situations, rear door ECUs may only be accessible through front door ECUs.  

In newer vehicles with more complex cybersecurity gateway modules, additional barriers may be present. These gateway modules often need to be updated themselves first to unlock access to the rest of the network. 

Power requirements also matter. Some modules rely on others to provide wake-up signals or power stability. Even the ignition key position can affect access: one ECU may require the key to be in the On position, while another may need it to be in the Accessory position. 

Practical limits to parallel reflashing 

Parallel reflashing makes the reflashing of multiple modules quicker, but it can’t make individual modules update faster. The longest module flash will typically set the minimum time for the total reflash time. For example, if one module takes 65 minutes and the others are all between 30 and 40 minutes, the full vehicle reflash will still take a minimum of 65 minutes. However, that’s significantly faster than reflashing each module one by one, which would take several hours. 

In bench reflash situations, CAN channel count is usually the bottleneck. In-vehicle reflashing, especially with Ethernet, enables greater scalability — assuming the OEM’s architecture supports it. 

Gateway limitations, software design, and how an OEM has structured its internal reflashing tools also play a role. Some platforms allow broad access for parallel operations, while others are more restrictive for security reasons. 

Why it matters 

The primary benefits of parallel reflashing are time and efficiency. With every hour saved, costs typically drop as well: fewer technician hours, less wear on equipment, lower battery load, and reduced yard or line-side storage costs. 

In many situations, faster reflashing directly leads to reduced facility costs. Quicker reflashing improves throughput, which helps reduce storage time for both parts and vehicles. This leads to lower warehouse and lot costs, resulting in meaningful savings. 

Also, when technicians reflash multiple modules at once, they aren’t constantly switching tools or reconfiguring setups. They can start a job and monitor several vehicles or modules in parallel rather than handling one at a time. 

For example, consider an emergency reflash situation where nine modules need to be reflashed across 1,000 vehicles. A sequential approach would take approximately three hours per vehicle, with the longest module flash lasting 50 minutes. With parallel reflashing, technicians can do the same job in one hour. That translates into eight vehicles per day instead of just three. For a five-person team, the entire job would finish in 25 days with parallel reflashing versus 70-80 days for the same team using sequential reflash techniques. 

This kind of efficiency has real consequences. Reflashing delays can hold up vehicle shipments, trigger penalties, or cause OEMs to miss delivery targets. Parallel reflashing helps mitigate these risks while freeing up teams for other critical tasks. 

Beyond reflashing: parallel diagnostics 

Parallel techniques are now being applied to diagnostics as well. OEMs are beginning to see the benefits of running health checks, fault code retrievals, and validation routines across multiple modules simultaneously.  

This can be a game-changer in plant production environments or during pre-delivery inspections where time is tight. 

The Movimento advantage 

Most reflash service providers don’t offer true parallel reflashing. At least not at scale and not with support for diverse architectures. Some OEMs have internal tools that handle specific use cases, but these tools are typically limited in scope. 

Movimento is one of the only service providers offering configurable parallel reflashing solutions that can adapt to different vehicle platforms. Whether an OEM has its own software stack or needs a complete turnkey solution, Movimento’s teams can integrate quickly, usually within 24 hours, and begin deploying reflashing operations across fleets or assembly lines. 

For OEMs and suppliers looking to plan ahead, a Movimento preparedness campaign is a zero-risk way to ensure reflash situations are dealt with as quickly and efficiently as possible.  

Movimento also offers full traceability through its Nuvolo cloud software, giving customers real-time visibility into progress, success rates, and any faults encountered during reflashing. 

Final thoughts 

Parallel reflashing addresses a very real problem for OEMs and Tier 1 suppliers: how to update increasingly complex software environments without crippling production or post-production timelines.  

Parallel reflashing is faster, more efficient, and often more reliable than traditional sequential methods. 

As vehicle software continues to grow in volume and complexity, the ability to scale reflashing — and diagnostics — will become a competitive necessity. OEMs and suppliers looking to stay ahead should be considering parallel solutions now, not later. 

To learn more about Movimento preparedness campaigns or for help with a current reflash challenge, contact us.