Category Archives: OBD-II

Freeze Frame Example

Freeze frame snapshots are made by the ECU and stored internally when it detects an error (DTC). A limited and pre-defined amount of values is being recorded.
Table shows actual sample from 2009/2010 Impreza Diesel (Euro4). First three columns listed exactly like dealership software (SSMIII) printout, additional columns were added as we happen to know how the system works.

Item Detect Unit OBD-II PID Comment #
Freeze frame data P0462 2 Diagnostic Trouble Code (DTC) 1
Calculated load value 0 % 4 = Injection Quantity / Max Allowed 2
Coolant Temp. 19 °C 5 3
Mani. Absolute Pressure 100 kPa B 4
Engine Speed 0 rpm C 5
Vehicle Speed 0 km/h D 6
Intake Air Temp. 19 °C F Manifold Air Temp 7
Mass Air Flow 0.8 g/s 10 8
Throttle Opening Angle 92 % 11 9
Time Since Engine Start 0 sec 1F 10
Common rail pressure 370 kPa 23 11
Number of warm-ups 12 30 since DTCs cleared, max 255 12
Meter since DTC cleared 182 km 31 Distance 13
Atmosphere Pressure 99 kPa 33 14
Catalyst Temperature #11 12.5 °C 3C EGT at Catalyst Inlet 15
Catalyst Temperature #12 12.5 °C 3E EGT at DPF Inlet 16
Control module voltage 12.851 V 42 Battery Voltage 17
Ambient Temperature 34 °C 46 Inlet Air Temp (air filter) 18
Accelerator Pedal Pos.#1 13.3 % 49 Accelerator Main Sensor 19
Accelerator Pedal Pos.#2 12.9 % 4A Accelerator Sub Sensor 20
Target Throt. Act. Cont. 79.2 % 4C Target Throttle Position 21

Freeze frame data can be retrieved using standard OBD-II mode 2 commands. PIDs do match sampling mode 1, see page OBD-II protocol or Wikipedia: OBD-II PIDs.
Generally, data items to be recorded are ROM specific, Euro5 and early diesel models (closed-type DPF, no exhaust temps) differ slightly for example. Expect around 15-25 items total.

By the way that P0462 Fuel Level Sensor Circuit (Low Input) is insignificant, caused by detection being set up too sensitive, we’ll correct this via patch.