How to take a freeze frame and what to read in it
The table the unit saved at the moment of the fault answers half the questions.
Take the freeze frame BEFORE clearing the code
A freeze frame is a snapshot of the readings at the second the unit recorded the fault. A reset wipes it along with the code, and nothing can bring it back. Take it first, think about clearing later.
Look at revs and speed
They tell what the car was doing: idling, accelerating or cruising. A fault at zero speed and low revs is an idle problem; at high revs under load, look at fuelling and ignition.
Check the temperature at the moment of the fault
A cold engine in the freeze frame means the fault happened during warm-up — a completely different set of causes than the same code when hot. This single number often halves the list of suspects.
Compare load with what you remember
High load in the freeze frame while you «were driving gently» means the engine worked harder than it felt: a blocked exhaust, a slipping clutch, dragging brakes. A gap between memory and the number is a hint too.
Attach the freeze frame to the report for the mechanic
It tells a mechanic more than the code itself: the code names the system, the freeze frame names the circumstances. The conversation starts not with «I have a check light» but with «the fault was recorded cold, at idle, at 22 % load».