OBDII Freeze Frame Explained
The OBDII freeze frame is your snapshot view into what is wrong in your 1996+ vehicle. When your OBDII vehicle encounters a problem with a sensor or the engine is not returning values that your ECU expects, your check engine light will turn on. Your ECU determines the error based on several engine operating conditions and stores it in what’s called a OBDII freeze frame.
The OBDII Freeze Frame is considered one frame of information taken by an on-board data recorder. When a fault occurs, the PCM stores the input data from various sensors so that technicians can determine under what vehicle operating conditions the failure occurred.
The data stored in Freeze Frame is usually recorded when a system fails the first time for two consecutive trip faults. Freeze Frame data will only be overwritten by a different fault with a higher priority.
What is a OBDII Freeze Frame?
They are simply snapshots of what is wrong with your vehicle. These freeze frames are essential to diagnosis and fixing your OBDII vehicle by replacing the sensor or addressing the fault at hand. Erasing DTCs, either with the DRB III or by disconnecting the battery, also clears all Freeze Frame data.
Similar Conditions Window
The Similar Conditions Window displays information about engine operation during a monitor. Absolute MAP (engine load) and Engine RPM are stored in this window when a failure occurs. There are two different Similar conditions Windows: Fuel System and Misfire.
Fuel System Similar Conditions Window
An indicator that ’Absolute MAP When Fuel Sys Fail’ and ’RPM When Fuel Sys Failed’ are all in the same range when the failure occurred. Indicated by switching from ’NO’ to ’YES’. Absolute MAP When Fuel Sys Fail — The stored MAP reading at the time of failure. Informs the user at what engine load the failure occurred.
Absolute MAP — A live reading of engine load to aid the user in accessing the Similar Conditions Window.
RPM When Fuel Sys Fail — The stored RPM reading at the time of failure. Informs the user at what engine RPM the failure occurred.
Engine RPM — A live reading of engine RPM to aid the user in accessing the Similar Conditions Window.
Adaptive Memory Factor — The PCM utilizes both Short Term Compensation and Long Term Adaptive to calculate the Adaptive Memory Factor for total fuel correction.
Upstream O2S Volts — A live reading of the Oxygen Sensor to indicate its performance. For example, stuck lean, stuck rich, etc.
SCW Time in Window (Similar Conditions Window Time in Window) — A timer used by the PCM that indicates that, after all Similar Conditions have been met, if there has been enough good engine running time in the SCW without failure detected. This timer is used to increment a Good Trip.
Fuel System Good Trip Counter — A Trip Counter used to turn OFF the MIL for Fuel System DTCs. To increment a Fuel System Good Trip, the engine must be in the Similar Conditions Window, Adaptive Memory Factor must be less than calibrated threshold and the Adaptive Memory Factor must stay below that threshold for a calibrated amount of time.
Test Done This Trip — Indicates that the monitor has already been run and completed during the current trip.