The Power of the Pre-scan - A Snap-on^® Exclusive Advantage

Since 2014, pre-scan and post-scan functionality have been built into Snap-on® Diagnostic Software – not as an add-on, but as an essential part of the diagnostic process. And today, the most profitable technicians and workshops know that every vehicle should start with a pre-scan and end with a post-scan. It’s that simple. 

Comebacks happen - often they’re due to something being overlooked or a step missed in the rush of a busy workshop. But with the right tools and workflow, comebacks – and the costly time and reputation damage they bring – can be significantly reduced. 

Why a Pre-Scan Is Essential

Every pre-scan using a Snap-on® diagnostic tool performs a simultaneous code scan across both OBD-II and OEM protocols. Not checking both protocols is risking a comeback because you can have a code in one and not the other, or different codes in each. Doing both makes for a complete and accurate diagnostic picture from the outset, without the need for switching between menus or guessing which systems to focus on.  

Have you ever had a vehicle where someone worked on it before you and probably cleared the codes?    

Now you’re left without a clear trail to follow. That’s where OBD-II Permanent Codes come in. These trouble codes can’t be cleared with a scan tool. They stay stored in the system for up to 400 days—or until the vehicle completes two successful drive cycles without the fault returning. It’s a valuable feature that helps preserve essential diagnostic information and reduces the risk of misdiagnosis.

What’s more, the layout is fast, straightforward, and precise. Each module in the vehicle is individually assessed: 

• Green = Module is present and functioning correctly 
• Yellow = A module is present but has stored a Diagnostic Trouble Code (DTC)  
• Grey = A module is not responding 
• Not shown = The module is not used in the vehicle – unlike other tools that may display every possible module whether present or not, creating confusion and wasting time 

This distinction alone prevents misdiagnosis and ensures no time is wasted chasing systems that aren’t there. 

Fast-Track^® Intelligent Diagnostics: From Codes to Confident Decisions 

Once the pre-scan is complete, if any DTCs are found, the software displays a Diagnose button. Tap this and you’re taken directly to the Fast-Track® Intelligent Diagnostics landing page. Here’s where Snap-on® excels. 

Instead of navigating through hundreds of lines of data, technical service bulletins, and possible tests, our patented Fast-Track® troubleshooting workflow with filtered information, brings focus to the specific vehicle and code you’re working on. 

This includes:

• Commonly replaced parts specific to the DTC and vehicle  
• Pre-filtered functional tests and technical service bulletins (TSBs) help you confirm you’re on the right path to repair 
• Experienced-based information including the Top Repairs graph and verified Real Fixes show you how other techs have tackled the problem you’re facing. These verified fixes are harvested from billions of successful repair records 
• Patented Smart Data automatically selects only the PIDs related to the code you are working on, and flags which ones are out of range at idle. Instead of hundreds of possible readings, we only show you the ones that matter

It’s a targeted, vehicle-specific workflow that combines complaint, cause, and correction on one page. It leads you to pinpoint the problem with the least number of steps. 

Workflow That Works

The recommended diagnostic process looks like this: 

1. Pre-scan – Check all systems and log DTCs 

2. Diagnose – Guided by Fast-Track® Intelligent Diagnostics 

3. Test – Functional testing, Smart Data review 

4. Repair – Replace or rectify the fault 

5. Recalibrate – Perform necessary resets and relearns 

6. Post-scan – Confirm that all systems are functioning as expected 

In fact, the additional benefit of the pre-scan is that it often reveals extra work that may be needed – work that can be discussed and quoted before repairs begin. This prevents customer callbacks and ensures transparency. 

Beyond the Basics

Some scan tools offer a “topology” view – a diagram of how vehicle modules are connected. While this may appear helpful, these are generic templates and don’t reflect actual module configuration or data bus layout. This can be misleading and often causes further confusion. Snap-on® software engineers chose a better route: simple, direct, accurate, no guesswork - just clear visualization and actionable results.

Diagnostic Health Scan- For the Workshop and the Customer

Alongside the pre- and post-scan, Snap-on® Diagnostic Software offers the exclusive Diagnostic Health Scan functionality. This provides the same comprehensive full system scan data, which is displayed in a customer-friendly report with an easy-to-understand overview that explains the vehicles condition and identifies potential issues in a simple way.

Find out more about Snap-on® Diagnostic Health Scan functionality here: