How to read OBD2 freeze frame data

How to Read OBD2 Freeze Frame Data?

If you’re not a professional mechanic, understanding the symbols, numbers, and acronyms that OBD2 freeze frame data comes with is quite challenging. However, the OBD2 freeze frame data features vital information that can help you in diagnosing your car problems with OBD2 Tools.

The OBDII freeze frame data shows the PID or parameter ID values when the diagnostic trouble code list (DT) was triggered. PIDs monitor the emissions produced by the vehicle by burning the engine fuel. When your car has a fault, the vehicle’s onboard computer saves a freeze frame data snapshot of what was happening at the time of the event. As a result, this information is vital to comprehending the fault and rectifying the issue. Freeze frame data focused on:

  • RPM
  • Fuel system status
  • MAP sensor or MAF sensor
  • Engine load
  • Throttle position
  • Coolant temperature
  • MIL, EVAP, and EGR status
  • Vehicle speed and more…

What is freeze frame data?

An OBD2-compliant computer records snapshots of your vehicle’s operating conditions, just like how the airplane’s black box does for the aircraft. Vehicle manufacturers can decide when this takes place as long as they do it every time the malfunctioning indicator lamp turns on.

Regardless of whether it’s a single record or a complete table, freeze frame data is very crucial to diagnosing errors, and that’s why it’s never deleted or even overwritten. The information recorded stays in the computer’s buffer until it’s manually retrieved or cleared from an external gadget. So it is tricky to clear the OBD2 code from your dashboard.

Additional functions of freeze frame data

Apart from using the freeze frame data to know what was happening when the DTC was recorded, you can use the freeze-frame screen for other functions. These include:

  • Refresh the page with the recent data
  • Check the freeze frame history, which shows your previous data
  • View the diagnostic trouble code article
  • Clear active codes
  • Reset your emissions readiness monitor

How does the OBD2 system store freeze frame data?

If you desire to know how an OBD2 scanning system keeps the freeze frame data, it is crucial to comprehend the two types of system monitors. These are continuous monitors and two-trip monitors/non-continuous monitors.

  • Continuous monitors

This indicates that the monitors are constantly operating or running whenever the car is running. They include the misfire and fuel trim detectors. It is usually referred to as a ‘one trip’ emissions diagnostic monitor and will allow the powertrain control module to instantly keep a diagnostic fault code together with the necessary freeze frame data.  

  • Non-continuous/two-trip monitors

These monitors are slightly different from oxygen sensors, EGR systems, heaters, catalytic converters, and evaporative emissions. Unlike continuous monitors that conduct a test once a trip, the PCM in non-continuous monitors temporarily keeps a diagnostic fault code until the next trip. Besides, if the failure does not happen during the second trip, the temporary fault code will be cleared from the ECU memory.

On the same note, if the failure takes place during the next trip, the ECU will keep a DTC along with the appropriate freeze frame data.

How to read OBD2 freeze frame data easily?

How you read OBD2 freeze frame data depends on the type of scan tool you’re using. If you have a professional automotive OBD II scanner, reading the freeze frame data is super easy. And if you know how a modern car engine functions, the process becomes even easier.

Things like engine RPM, air flow rate, engine coolant temperature, and vehicle speed sensor are simple to comprehend. The information delivers a snapshot of what the engine sensors were doing when the fault code was triggered. Nevertheless, reading the OBD2 freeze frame will be pretty challenging if you have a more basic scanner.

Note that the saner will attempt to interpret the raw code to form something that you can read. Nevertheless, like any computer system, vehicles have their language. Thus, you may have the desire to learn the codes relevant to your car. This is important because the data provided may differ according to the vehicle’s make and model, the car’s OBD II protocol, and the type of scanner used.

Related article: How can you check engine light with the OBD2 scanner?

Freeze frame data and what they mean

Knowing how to interpret different freeze frame codes is vital regardless of the scan tool you use. Here are some of the standard OBD2 codes and their meaning:

  • P0420 – this type of fault takes place twice a month, and it is a sign that readiness codes are performing well.
  • RPM – this implies the RPM (engine) when the information was recorded.
  • Fuel SYS 1 CL – it indicates that the fuel injection bank is in closed-loop mode.
  • Fuel SYS 2 N/A – it implies that there is no fuel injection in bank 2. Also, it indicates that it’s an inline 4/6 cylinder engine.
  • Load PCT 87 – it shows that the air entering the motor is below 100%.
  • IAT 57 – it’s a sign that Intake Air Temperature was at 57 degrees F when the PCM detected the diagnostic trouble code.
  • ECT (F) 221 – it’s for the engine coolant temperature.
  • VSS (mph) – this is the speed of the engine when the DTC was recorded.
  • SHrtFT1 2.6 – it shows that the short-term fuel trim is at 2.6%.  
  • P0301 = misfire in cylinder 1, which isn’t burning fuel properly.
  • Load (%) 92.1 = mass of the intake air per intake stroke as a percentage (95%).
  • Long FT 1 (%) -3.1 = ECU was subtracting fuel
  • MAP (kPa) 26.7 = Manifold absolute pressure in kPa

How can you access the freeze frame?

If you want to access the freeze frame data, you will have to use a quality OBD2 scanner like Autel TPMS TS601 or OTC Encore WI-FI enabled diagnostic tool. Not all scan tools will display freeze frame data, and that’s why you need to acquire or hire a quality scanner.

After you acquire the scanner, you will connect it to your car via the OBD2 port. Next, the scanner will show the data and its DTCs and an icon that’s similar to a camera. The list will also feature the error code description and status. If your OBD2 port is not working, check the fuse and circuit.

You can view the data by choosing the entry and then clicking the view freeze frame button. The button will open a window with the frame’s controls and data.    

How to use freeze frame data?  

Depending on the present data, a freeze-frame can pinpoint whether the engine was cold or warmed or what the temperature was outside. Besides, it can indicate at what RPMs the fault took place, at what speed, and how much time passed when the engine was started.

Related article: What is OBD2? Easy explanation to understand this automotive scanning system

Additionally, the freeze-frame can tell the fuel level in the tank and battery voltage at that time. Having this data is very vital as it can point your diagnostic effort in the right way. Moreover, the freeze frame data can help diagnose random issues. Sometimes, a random issue can trigger the check engine light to come on, but everything is fine when the mechanic inspects the car using a code reader. On the contrary, the freeze-frame can show what sensor reading was out of specs.  

Bottom line

Understanding how to view and read the freeze frame data is crucial for diagnosing car problems. It allows you to know what was happening when the problem occurred. However, you will need a quality diagnostic OBD2 scan tool to read freeze frame data and get all the crucial data that will help you to diagnose your vehicle properly.

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