Freeze Frame

The state of the car at the instant the fault was recorded, the most useful piece of the diagnosis.

When it records a fault code, the ECU also stores a snapshot of the conditions at that instant: engine speed, load, temperature, speed and fuel trims. That snapshot is the Freeze Frame.

It is what tells a generic misfire apart from a misfire at 900 rpm with a cold engine. The code is the same, and the problem is not.

  1. Choose the reading method

    The screen has three tabs. Standard sweeps several frames of OBD-II mode and serves most cars. Pro reads by fault code, requires the CAN protocol and is the one for deeper diagnosis. Legacy reads the first frame only, for older cars without CAN.

  2. Take the reading

    With the adapter connected and the ignition on, tap Read. The screen shows the progress while it queries the ECU.

  3. Read the table

    The result comes in three columns: PID, Description and Value. Use the search field to find the reading you want quickly.

  4. Start from Diagnostics, on the Pro tab

    The Pro reading works by fault code, and therefore depends on a code being stored. If the app says it found no error with a snapshot, open Diagnostics and run a Professional scan first.

  5. Read before clearing

    Clearing the codes also erases the freeze frame. Take the reading and write the values down before clearing, or you lose exactly the information that would help locate the cause.

If something goes wrong

In most cases there is no fault code stored, and with no fault there is no freeze frame. Run a scan in Diagnostics to confirm.

That tab reads by code, and depends on a stored code that carries a snapshot. Open Diagnostics and run a Professional scan first.

It requires the CAN protocol, which older cars do not have. On those vehicles use the Legacy tab, which reads the standard frame of OBD-II mode.

Clearing the errors erases the freeze frame with them, and there is no way to get it back. Next time it happens, take the reading and write the values down before clearing.

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