ECU Data Values

The values returned by the ECU are raw values that are not necessarily directly related to the human readable values (e.g. fuel trim is an integer with positive and negative values, the ECU returns 128 as the value for 0 trim adjustment). The values displayed are human readable values that have had calculations applied (see table for applied calculations).

The ECU data is recorded to a log file that can be viewed in Excel / Google Sheets along with indicative analysis metrics. See the diagnostic tree for the analysis determination.

ColumnDescriptionCalculation Applied
#timeevent timestamp hh:mm:ss.sss
80×01-02_engine-rpmengine rpm
80x03_coolant_tempthe temperature in degrees Celsius read from the Coolant Temperature Sensor (CTS). This sensor can be found under the injector unit. An essential value in the air:fuel ratio calculationvalue – 55
80x04_ambient_tempnot used by the ECU, always returns 255value – 55 = 200
80x05_intake_air_tempthe temperature in degrees Celsius read from the Air Intake Temperature Sensor (ATS). This sensor can be found under the air filter. An essential value in the air:fuel ratio calculationvalue – 55
80x06_fuel_tempnot used by the ECU, always returns 255value – 55 = 200
80x07_map_kpamanifold absolute pressure (MAP). Reads pressure from the back of the injector unit via the vacuum pipes and fuel trap. An essential value in the air:fuel ratio calculation
80x08_battery_voltagethe battery voltage. A figure <12 volts will cause running issuesvalue / 10
80x09_throttle_potthrottle potentiometer position. used by the ECU to determine throttle position when controlling idle speedvalue * 0.02
80x0A_idle_switchshows the state of the throttle switch, fitted on early vehicles. On systems without an actual throttle switch, the value shown indicates whether the MEMS ECU has calculated that the throttle is closed by using the throttle position sensor. If the switch shows ‘ON’ when the throttle is closed, then the vehicle will not idle correctly and the closed throttle position may need to be reset. This procedure is performed by fully depressing and releasing the accelerator pedal 5 times within 10 or fewer seconds of turning on the ignition and then waiting 20 seconds.
80x0B_uk1unknown value
80x0C_park_neutral_switchused on vehicles with an automatic gearboxtrue / false
80x0D-0E_fault_codesECU fault codes:
Coolant temp sensor fault (Code 1)
Inlet air temp sensor fault (Code 2)
Fuel pump circuit fault (Code 10)
Throttle pot circuit fault (Code 16)
80x0F_idle_set_pointadjusts the idle rpm by the value shown. Adjusting idle speed will modify this value
80x10_idle_hotthe number of IACV steps from fully closed (0) which the ECU has learned as the correct position to maintain the target idle speed with a fully warmed-up engine. If this value is outside the range 10 – 50 steps, then this is an indication of a possible fault condition or poor adjustment.value – 35
80x11_uk2unknown value
80x12_iac_positionInlet Air Control valve (IACV) position (relates to expected Stepper Motor position)
80×13-14_idle_erroridle speed offset (also known as idle speed deviation)
80x15_ignition_advance_offsetadjustment to the ignition timing
80x16_ignition_advanceignition advance, value of 128 = 0(value / 2) – 24
80×17-18_coil_timecoil timing in msvalue * 0.002
80x19_crankshaft_position_sensorposition of the crankshaft from the position sensor (CPS)
80x1A_uk4unknown value
80x1B_uk5unknown value
7dx01_ignition_switchstatus of the ignition switchtrue / false
7dx02_throttle_angleshows the position of the throttle disc obtained from the MEMS ECU using the throttle potentiometer. This value should change from a low value to a high value as the throttle pedal is depressed.value * 6 / 10
7dx03_uk6unknown value
7dx04_air_fuel_ratiothe current air:fuel ratiovalue / 10
7dx05_dtc2diagnostic trouble code – unknown codes
7dx06_lambda_voltagethe voltage read from the lambda sensorvalue * 5
7dx07_lambda_sensor_frequencynot used by the ECU, the value reads 255
7dx08_lambda_sensor_dutycyclenot used by the ECU, the value reads 255
7dx09_lambda_sensor_statusECU O2 circuit status, 1 active
7dx0A_closed_loopECU has entered a closed loop and uses the lambda sensor for determining air:fuel ratio
7dx0B_long_term_fuel_trimlong term fuel trim (LTFT) displays ECU value to adjust fuelling. value of 128 = 0value – 128
7dx0C_short_term_fuel_trimshort term fuel trim (STFT) displays ECU value to adjust fuelling
7dx0D_carbon_canister_dutycyclenot used by ECU, value reads 0
7dx0E_dtc3diagnostic trouble code – unknown codes
7dx0F_idle_base_posthe base value to offset idle position from
7dx10_uk7unknown value
7dx11_dtc4diagnostic trouble code – unknown codes
7dx12_ignition_advance2ignition advancevalue – 48
7dx13_idle_speed_offsetidle speed offset used to adjust idle speed
7dx14_idle_error2idle error
7dx14-15_uk10unknown value
7dx16_dtc5diagnostic trouble code – unknown codes
7dx17_uk11unknown value
7dx18_uk12unknown value
7dx19_uk13unknown value
7dx1A_uk14unknown value
7dx1B_uk15unknown value
7dx1C_uk16unknown value
7dx1D_uk17unknown value
7dx1E_uk18unknown value
7dx1F_uk19unknown value
0x7d_rawhexadecimal response from the ECU for command 0x7D
0x80_rawhexadecimal response from the ECU for command 0x80
engine_runningengine is runningtrue / false
warmingthe engine is warming up to operating temperaturetrue / false
at_operating_tempthe engine is at operating temperaturetrue / false
engine_idleengine is idletrue / false
idle_faulthot or cold idle speed or idle offset is outside expected parameterstrue / false
idle_speed_faultcold idle speed is outside expected parameterstrue / false
idle_error_faultidle offset is outside expected parameterstrue / false
idle_hot_faulthot idle speed is outside expected parameterstrue / false
cruisingrpm is stable but not idle; the engine is cruising (differentiates from idle)true / false
closed_loopECU is operating in closed loop (using lambda to determine air:fuel ratio)true / false
closed_loop_expectedexpecting the ECU to be in closed looptrue / false
closed_loop_faultclosed loop faulttrue / false
throttle_activethe throttle pedal is depressedtrue / false
map_faultMAP readings is outside expected parameterstrue / false
vacuum_faultMAP and Air:Fuel ratio are outside expected parameters indicating a possible vacuum pipe faulttrue / false
iac_faultIAC position is invalid if the idle offset exceeds the max error, yet the IAC Position remains at 0true / false
iac_range_faultIAC readings outside expected parameterstrue / false
iac_jack_faulthigh jack count indicating a possible problem with the stepper motor, throttle cable adjustment, or the throttle pottrue / false
o2_system_faultdetected a potential o2 system faulttrue / false
lambda_range_faultlambda sensor readings are outside expected parameterstrue / false
lambda_oscillation_faultlambda sensor not oscillating as expectedtrue / false
thermostat_faultcoolant temperature changes over time indicate thermostat fault (could also be a CPS fault)true / false
crankshaft_sensor_faultcrankshaft position sensor (CPS) reading is outside expected parameterstrue / false
coil_faultthe coil is outside expected parameterstrue / false