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OBD2 Freeze Frame Data: How to Interpret And Use It?

OBD2 freeze frame data lets you properly diagnose and troubleshoot problems on a vehicle. Read this article, follow the simple steps to use the data.

When something goes wrong, a vehicle’s onboard computer saves a freeze frame data snapshot of what was happening at the time of the incident. This data is crucial to understanding what went wrong and how to repair it.

However, you must download and read this data from the computer to use it. You can do this in a variety of ways depending on the state of the engine, but you will need an appropriate tool to actually read and use the data.

The OBD2 Standard

obd2 connector.

OBD2 Connector.
Source: wikimedia.org

All vehicles built since 1996 have an On-Board Diagnostic Version 2 (OBD2) computer that self-checks the vehicle for problems and other issues.

The OBD2 Standard is a much more sophisticated version of the 1990’s original OBD1 California standard. It defines what diagnostic system components and protocols must be present in all vehicles sold in the United States. It also specifies what parameters to monitor

Finally, OBD2 provides a list of standard diagnostic trouble codes (DTC), accessible through a universal system access port. While originally only for emission control systems, most manufacturers now use this OBD2 Data Link Connector for all diagnostic and reprogramming tasks.

What is Freeze Frame Data?

OBDII Freeze Frame

OBD2 Freeze Frame Data.

Just like an airplane’s black box, an OBD2-compliant computer records snapshots of the operating conditions of your vehicle. Manufacturers can set how often this happens as long as they do it whenever the malfunction indicator lamp (MIL) lights up. We call this particular snapshot a freeze frame, and its data freeze frame data.

Either be a single record or a complete table, freeze frame data is so important to diagnosing faults that it is never deleted or overwritten. The data remains in the computer’s buffer until manually retrieved and cleared from an external device.

Other Freeze Frame Data Functions

Beyond the basic reading functions, most professional OBD2 scanners will modify and reprogram the system as needed. Some of these functions include refreshing the page to get the latest data from the computer.

Some scanner models will even let you read the freeze frame history of the vehicle, which you can read on the tool itself or on your mobile device. This data lets you see if you have a reoccurring problem that might indicate that there is an even worse problem underneath. You can then clear the frame to resent the entire system back to its normal operating mode.

How to Access a Freeze Frame?

To read and clear the data, you must attach an OBD2-compliant scanner. Manufacturer-authorized mechanics have manufacturer-specific scanners that resemble laptop PC that will display everything the computer records. A generic, off-the-shelf scanner will be much more limited, and can easily diagnose any Check Engine light problem.

Either way, the scanner will display the data along with its DTC and an icon that resembles a camera. The list will also include the fault’s description and status. You access the data by selecting the entry and then clicking the view freeze frame button. The button will open a window containing the frame’s controls and information. You can stack this window vertically to access multiple frames side-by-side at once.

How to Read Freeze Frame Data?

Because of how important freeze frame data is to your diagnostic efforts, you want an easy way to understand what the data is telling you. A good scanner can let you get the data off the computer, but you have more work to do from there.

Sure, your scanner will try to interpret the raw code to create something you can read it. However, like any computer system, cars have their own language. Therefore, you may want to learn the codes relevant to your vehicle.

Fortunately, we have demystified many of the more common OBD2 DTC in the table below.

DTC Meaning/ Interpretation.
Absolute map This is a live reading of the vehicle. Use it to look for similar conditions.
PO 420 errors An automatic self-test. These deliberate faults happen twice a month.
Load PCT 92.2 The air entering the engine is below 100%.
RPM The RPM of the engine at the time of recording.
Upstream O2S Volts Live performance reading of the oxygen sensor.
Fuel SYS 2 N/A No fuel injectors in the bank 2.
Fuel system good trip counter Trip counter that turns off the MIL for the fuel DTC
systems.
ECT (F) 221 Engine temperature.
Test done this trip Monitor already ran and completed during the current
trip.
VSS MPH Vehicle engine speed when the data was recorded.
Fuel SYS 1 CL Fuel injection bank is in closed loops.

How to use Freeze Frame Data?

A freeze frame can tell you the full state of the engine at the time of the fault. It can tell you if the engine was hot or cold. It can tell you what the weather was through the Intake Air Temperature (IAT). It can even give you the speed of the engine and tires at the moment of the fault, as well as how long the engine was on at the time. Other common freeze frame data include fuel levels and battery voltage. You will even know how many times the fault occurred since the last diagnostic check.

All this information helps you figure out what went wrong with the vehicle. You never have to dig in blindly as you always have something to guide your efforts. The data can even flag false alarms and intermittent problems from say a low fuel condition from an otherwise healthy engine.

The data may give you the sensor that triggers the fault. For instance, freeze frame data may reveal faulty or corroded battery contacts by reporting improper battery voltage levels. Either way, you may want to check the freeze frame data if everything else is giving you “no communication” codes or is otherwise giving you wrong information.

Conclusion

In summary, utilizing the OBD2 freeze frame data, you can properly interpret the information coming from your vehicle.  You will need an appropriate scanner to get the data, but it is worth the effort and you can begin troubleshooting your vehicle. We hope you will have the tools you need to properly find the root cause of any problem, increasing the speed and effectiveness of your repairs.

Read more: OBD1 vs OBD2: Definite Interpretation and Comparison

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