#Automobilindustrie

What is freeze frame data?

twitterfacebook
What is freeze frame data?
Freeze frame data is a collection of parameter IDs that are stored in a vehicle’s Engine Control Unit (ECU) whenever a Diagnostic Troubleshoot Code (DTC) is triggered. 
 
These parameters may be: RPM, battery voltage, ambient air pressure, vehicle speed, engine load, intake and coolant temperature, and much more.
 
The DTC in question influences how much data is stored in a freeze frame. Some DTCs will be a lot more detailed in their freeze frame data.
 
Since freeze frame data displays the exact running conditions when an issue arose, it’s invaluable for diagnostics. And figuring out what that pesky Check Engine Light (CEL) is all about.


How does freeze frame data work?


Freeze frame data is recorded whenever the same problem occurs several times in your vehicle. Manufacturers define what constitutes an intermittent problem (i.e., how many times it should occur). 
 
Here’s how it works:
 
All vehicles manufactured post-1996 have two categories of malfunction detection: “Pending” and “Logged.” 
“Pending” means a malfunction has been detected, and a DTC has been assigned, but it hasn’t occurred frequently enough yet. Frequency is defined by the manufacturer. 
 
Yet, the fault can be promoted to “Logged,” which is when the issue has passed the frequency threshold. Most “Logged” trouble codes will be stored with freeze frame data with the aforementioned information on running conditions.
 
Once one or more default fault codes have been logged, the CEL light is turned on. Not that it’s very useful by itself. That’s why you need an OBD diagnostic reader or any other similar tool.
 
OBD readers can access freeze frame data. Here’s how it would look with OBDeleven:
 

 

What parameters can you find in freeze frame data?


There can be major differences in the way vehicles store freeze frame data. These are dependent on the trouble code as some will provide more extensive information than others.
 
With most fault codes you’ll get information such as:
 
  • Fault priority – the importance of the detected fault. Can range from 1 to 7 with 1 being the most critical and 7 the least critical faults. Numbers 0 and 8 are reserved for other information.
  • Malfunction frequency counter – the number of times faults have occurred during all driving cycles. Can vary from 0 to 254.
  • Unlearning counter – the number of fault-free driving cycles that remain before the ECU clears the fault code(s).
  • Outside air temperature – exactly what it says on the tin: the logged air temperature outside of the vehicle when the fault code was triggered.
  • Engine speed – RPMs recorded when the freeze frame data was captured.
  • Engine coolant temperature – again, exactly what you’d expect: it’s the captured coolant temperature when freeze frame data was logged, and the fault code was set.
 
And much more. Modern vehicles may record vast amounts of freeze frame data, depending on the DTC. You can find information about mileage, engine speed, normed load value, or any other parameters you can imagine.
 
Try wireless car reader


How to read freeze frame data


All OBD scanners will have their differences when displaying freeze frame data. When using the OBDeleven scanner to read freeze frame data, first you'll need to scan your Volkswagen Group (VAG) vehicle using the OBDeleven VAG app. 
 
Then, from the Control Units section, click on the specific unit where faults were found (it'll have a red number at the top left), like here:
 
 
 
 
Let's take Engine as an example. You'll get a list of fault codes:
 
 
 
Clicking on the specific fault code will open up the freeze frame data menu. That’s where you’ll see all the captured parameters when the issue was detected:
 
 
Other OBD readers will display a table or menu that lists the identified fault and freeze frame data. Depending on the capabilities of the device, you may also get manufacturer specific faults along with the freeze frame data.
 
Manufacturer-specific fault codes can reveal information that general-purpose DTCs do not cover. They can help in finding a solution as they may be more specific to your vehicle.


Freeze frame data vs live data


Live data recording is a feature offered by some advanced OBD2 tools. While it’s often compared to freeze frame data, there’s some important differences.
 
First, the time of data logged. Live data is only available if the OBD diagnostic tool is connected and recording. Freeze frame data can be logged whenever the vehicle is operating, although it’s typically accessed through the same tools.
 
Additionally, the scope of recorded data will differ for all issues, which can either help or hinder analysis. Live data scope, on the other hand, remains the same at every point in time and may also show information not tied to any issue currently occurring such as engine speed or fuel consumption.
 
Finally, both of these monitoring tools have slightly different applications. Both freeze frame and live data are immensely useful for automotive diagnostics. 
 
The former, however, showcases the parameters at the exact moment the fault occurred. Live data shows what’s happening at present.
 
Further reading: How to read OBD live data 


Frequently asked questions about freeze frame data


Is it possible that there’s no freeze frame data stored?

Most errors have freeze frame data. Not all trouble codes (including manufacturer-specific codes) will have freeze frames, however, a larger part of them will.
 
Major differences lie in how much data is logged when the code was set. Different codes will typically have different amounts of data in their freeze frame.

Can I reset the freeze frame?

Yes. Freeze frames are typically tied to a specific fault code. If you have an OBD tool that’s compatible with your vehicle and has the ability to clear codes, doing so will remove the freeze frame.
 
While doing so will reset the CEL light, it doesn’t solve the underlying problem. It’s likely that the same problem will appear again later on, so it’s often better to run automotive diagnostics and fix the issue instead of simply clearing the code.

Are there freeze frames that don't turn on the Check Engine light?

Yes. While most general fault codes turn on the Check Engine light, manufacturer-specific ones may not do so. It’s a good idea to regularly check your car for any troubles and perform preventative maintenance instead of waiting for a light to pop up.