Live Data Guide

Datapoint

Description

Vehicle Operation

Engine RPM

Engine RPM

Vehicle Speed

Vehicle speed

Engine Coolant Temperature

Coolant temperature - usually measured at the cylinder head or before the radiator.
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Some vehicles may report a second coolant temperature sensor (ECT 2) - location may vary (for example it may be at the outlet of the thermostat) - the factory manual or a parts diagram for your vehicle should provide more information

Engine Oil Temperature

Temperature of the engine oil - sensor may be situated near the oil filter but this location will vary depending on the vehicle

Ambient Air Temperature

Air temperature around the vehicle - typically this will be a few degrees below intake temperature

Barometric Pressure

Local ambient or atmoshperic pressure around the vehicle displayed as an absolute value
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Typically ambient pressure will read roughly 101.3 kPa or 14.7 psi, but this will vary depending on your altitude and local conditions

Accelerator Pedal Position

Position of the driver's accelerator pedal - there may be up to three sensors:

Relative Accelerator Pedal Position

Accelerator pedal position adjusted for the learned behavior of the vehicle over time.
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Due to scaling, the vehicle may not always report 100% when the pedal is placed to the floor.
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Depending on the vehicle this value may also be the average of multiple position sensors (D, E, F)

Commanded Throttle Actuator

The throttle position requested by the ECM based on accelerator pedal position

Relative Throttle Position

Throttle position relative to the "learned" or "adapted" closed position
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Over time throttle behavior can change due to carbon buildup or other factors, some vehicles will monitor this behavior and make adjustments over time to compensate
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For example: Over time carbon builds up in the throttle body and when "fully" closed, the throttle is actually open 5% - in this case the absolute throttle positon will read 5% while the relative position will read 0%

Absolute Throttle Position

How 'open' the throttle is - a value of 0% means completely closed while 100% is fully open
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Depending on the vehicle there may be up to four throttle position sensors:

Control Module Voltage

Input voltage at the Engine Control Module

Hybrid Battery Pack Remaining Life

AKA State of Charge
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The total charge percent remaining in the hybrid battery pack (individual cell data is not available through standard OBDII data)

Hybrid/EV Vehicle System Status

This parameter will report the following (as supported by the vehicle):

Calculated Engine Load Value

A calculated value representing the current percentage of maximum available engine torque being produced (100% at WOT, 0% at key on engine off)

Absolute Load Value

A normalized value representing the air mass intake per intake stroke as a percentage
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Calculation: (mass of air in grams per intake stroke) / (mass of air per intake stroke at 100% throttle assuming standard temperature and pressure)
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​Note: This datapoint has a reporting range from 0% to 25,700% but naturally aspirated engines will display roughly 0 to 95% while turbo/supercharged motors may show as high as 400%.

Driver's Demand Engine - Percent Torque

The percentage of maximum available engine torque requested by the ECM based on:

External factors such as traction control, abs, etc will not influenece this value

Actual Engine - Percent Torque

Also referred to as Indicated Torque
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This parameter displays the current percentage of total available engine torque and includes the net brake torque produced as well as the 'friction' torque required to run the engine at no load.

Engine Friction - Percent Torque

The percent of maximum engine torque required to run a 'fully equipped' engine at no load, this includes:

This value does not account for:

Engine Reference Torque

The torque rating of the engine - this is considered to be the 100% value for datapoints such as "Actual Engine Percent Torque" or other parameters that express torque output as a percentage.
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​Note: This value is set in the factory and does not reflect changes over time due to wear/aging, aftermarket upgrades/tunes, etc

Engine Percent Torque Data

This parameter is used in cases where changes in vehicle/environmental conditions can cause the reference torque to change - for example at high altitude a different fuel mapping may be employed which will decrease the total available torque by 80%.
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Up to five different maximum torque ratings may be specified with this datapoint, each rating is numbered 1 through 5.
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The datapoint does not report the reason for the change in maximum rating - a factory manual may be required to determine conditions related to each mapping.

Auxiliary Input/Output

This is a composite datapoint that is capable of reporting (if supported by the vehicle):

Note: Support for this datapoint is relatively rare, most vehicle report transmission status through non-standard enhanced live data

Exhaust Gas Temperature (EGT)

Depending on the vehicle the followng parameters may be reported for each exhaust bank:

Note: the above are based on a generic sample vehicle and may not apply to your specific configuration, for exact measurement points refer to the vehicle's factory manual

Engine Exhaust Flow Rate

Exhaust flow rate in kg/hr or lbs/hr measured upstream of the aftertreatment system, averaged over the last 1000ms

Exhaust Pressure

Exhaust pressure, displayed as an absolute pressure value - engine off this paramater should display roughly ambient atmospheric values.
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Depending on vehicle configuration this paramater may report data from one or two exhaust banks. For sensor/measurement location refer to your factory manual.

Manifold Surface Temperature

Temperature at the outer surface of the exhaust manifold

Timing Advance for #1 cylinder

The angle (in degrees) of crankshaft rotation before top dead center (BTDC) at which the spark plug for #1 cylinder starts to fire.
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A negative value indicates that the spark plug fires after cylinder #1 reaches the top while a positive value indicates adplug firing

Engine Run Time

This parameter reports the follow data (as supported by the vehicle):

Run Time Since Engine Start

Run time in seconds since the engine was last started

Time Run with MIL On

Engine run time since check engine light was activated after throwing a code
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​Note: Engine run time is different from total elapsed time - for example if the check engine light came on six months ago and you drove an average of 30 minutes per day this value will show roughly 5,400 minutes or 90 hours (3.75 days)
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This value will stop increasing when it reaches 65,535 minutes (roughly 45 engine-days)
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On Hybrids or vehicles with an auto Stop/Start feature this timer will continue to increase as long as the ignition is on, whether the actual engine is running or not

Distance Traveled while MIL is Activated

The distance driven since the check engine light last illuminated (reset when codes are cleared or the battery is disconnected)

Time since Trouble Codes Cleared

Engine run time since codes were last cleared (either by a scan tool or disconnecting the battery)
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​Note: Engine run time is different from total elapsed time - for example if codes were cleared two weeks ago and you drive an average of 45 minutes per day this value will show roughly 630 minutes or 10.5 hours
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This value will stop increasing when it reaches 65,535 minutes (roughly 45 engine-days)
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On Hybrids or vehicles with Stop/Start this timer will continue to increase as long as the ignition is on, whether the actual engine is running or not

Distance Traveled Since Codes Cleared

Distance traveled since engine codes were cleared with a scan tool or the battery was disconnected
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​Note: clearing non-engine codes (e.g. just clearing ABS) will not reset this value

Warm-ups Since Codes Cleared

Number of engine warm-up cycles since codes were last cleared (or the battery was disconnected)
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A warm-up cycle is defined as:

Once the counter reaches 255 it stops increasing
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​Note: clearing non-engine codes (e.g. just clearing SRS) will not reset this value

Datapoint

Description

Fuel & Air

Fuel System Status

Whether your vehicle is running in 'open' or 'closed' loop mode.

​Note: This datapoint reports the current status for two fuel systems (A & B) - these represent two distinct systems (e.g. CNG & diesel) on one vehicle as opposed to bank numbers. Most passenger vehicles will have one fuel system only and will report system B as open loop at all times.

Oxygen Sensor Voltage

O2 sensor voltage (see How are O2 Sensors Displayed?)
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For more information on O2 sensor operation and interpretation see Walker's O2 Sensor Training Guide

Oxygen Sensor Equivalence Ratio

O2 sensor equivalence ratio - aka Lambda (see How are O2 Sensors Displayed?)

Oxygen Sensor Current

Similar to O2 sensor voltage:

Short Term Fuel Trim

Fuel injection rate adjustment based on rapdily changing data from the O2 sensors.

Short term fuel trim is combined with long term fuel trim for a net correction to be applied to the injection rate
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​Note: Many vehicles will not use fuel trim from the post-cat sensors, in this case fuel trim will be displayed as 99.2%

Long Term Fuel Trim

Similar to short term trim, long term fuel trim reacts less readily to sudden changes and represents the 'learned' behaviour of the vehicle over a longer period.

Note: Many vehicles will not use fuel trim from the post-cat sensors, in this case fuel trim will be displayed as 99.2%
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Commanded Equivalence Ratio

The fuel:air ratio requested by the ECM, displayed as a lambda value (>1 lean, <1 rich, ~1 ideal ratio)
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Vehicles with wide range O2 sensors:

Vehicles with conventional O2 sensors:

Mass Air Flow Rate

The flow rate of air traveling through the intake in g/s or lb/min
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On turbocharged vehicles the MAF will be upstream of the turbo

Intake Air Temperature

Temperature of the air traveling through the intake.
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Turbocharged vehicles may have two IAT sensors - sensor #1 before the turbocharger and sensor #2 downstream of the turbo.
Depending on vehicle configuration there may also be two intake tracts in which case sensor data may be reported for banks 1 and 2.
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In normal operation the intake temperature should be slightly above the ambient air temperature

Intake Manifold Absolute Pressure

Pressure measurement inside the intake manifold.
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For turbocharged applications this represents the pressure at the manifold, after the turbo/intercooler/etc
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​Note: This is an absolute pressure value:

Fuel Pressure (Gauge)

Fuel pressure value.
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​Note: This is a gauge value - a value of 0 indicates atmospheric/ambient pressure

Fuel Rail Pressure

Pressure in the fuel rail displayed as a gauge value (0 psi/kPa means an atmoshperic/ambient pressure reading)

Fuel Rail Pressure (Absolute)

Pressure in the fuel rail displayed as an absolute pressure value - when the fuel rail is not presurized this datapoint will display ambient pressure - roughly 14.7 psi or 101.3 kPa

Fuel Rail Pressure (relative to manifold vacuum)

Fuel pressure value relative to the intake manifold

Alcohol Fuel %

The ethanol/alcohol content as measured by the engine computer in percentage.
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For example an E85 blend would show 85% for alcohol fuel percentage

Fuel Level Input

Percent of maximum fuel tank capacity

Engine Fuel Rate

Near-instantaneous fuel consumption rate, expressed in Liters or Gallons per hour
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Engine fuel rate is calculated by the ECM using the volume of fuel used during the last 1000 ms
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​Note: engine fuel rate does not include fuel consumed by diesel aftertreatment systems

Cylinder Fuel Rate

The calculated amount of fuel injected per cylinder during the most recent intake stroke - displayed in mg/stroke

Fuel System Percentage Use

This parameter displays the % of total fuel usage for each cylinder bank - up to a maximum of four banks.
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This datapoint will display data for two separate fuel systems (e.g. diesel & CNG) if supported by the vehicle.

Fuel Injection Timing

The angle (in degrees) of crankshaft rotation before top dead center (BTDC) at which the fuel injector begins to operate.
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A positive angle indicates injector operation before top dead center, while a negative angle indicates operation on the downstroke after TDC

Fuel System Control

This parameter reports the following status information for the fuel system on diesel vehicles (for fuel systems 1 & 2 as supported by the vehicle):

Closed loop indicates the system is using sensor feedback for fine tuning.
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​Note: Systems 1 & 2 refer to two separate fuel systems - system 2 may not be in use on most vehicles

Fuel Pressure Control System

This parameter displays the following data for up to two fuel rails - for sensor location refer to your factory manual:

Pressure is reported as a gauge pressure where 0 indicates rail pressure equal to the outside atmosphere.

Injection Pressure Control System

Some diesels use a pump to pressurize an oil rail which then transfers and multiplies this pressure via a piston to provide finer control over fuel injection pressures.
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The ICP sensor monitors the pressure on the oil side of the fuel system, depending on the vehicle this parameter will display:

Boost Pressure Control

Depending on the vehicle this parameter will show the following for one or two turbochargers:

Note: All data in this parameter is reported in absolute pressure - typically when discussing boost people will refer to gauge pressure. For example a value of 24.7 psi for actual boost pressure would be 10 psi gauge, or "10 lbs of boost". At idle before the turbo spools up this value will read at or slightly below ambient pressure which should not be confused with producing 14 lbs of boost.
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This parameter will also provide feedback on the operating mode of the boost control system, possible states are:

Turbocharger RPM

Measured turbine RPM of one or both turbos depending on vehicle configuration.
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​Note: This datapoint has a maximum value of 655,350 rpm so you may need to adjust your graph range settings when monitoring data in-app or it may appear as a straight line

Turbocharger Temperature

This parameter reports the following data for one or both turbochargers as supported by the vehicle:

Charge air temperatures have a range from -40 to 215 degC while the exhaust temperature reporting range is -40 to 6513.5 degC

Turbocharger Compressor Inlet Pressure Sensor

Pressure measured at the turbocharger inlet, for either one or two turbos depending on vehicle configuration
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This is an absolute pressure value, a value of roughly 14.7 psi / 101.3 kPa indicates atmoshperic pressure

Variable Geometry Turbo (VGT) Control

Vehicles with variable geometry turbos use motors or another method of actuation to change the orientation of vanes which will either direct the exhaust gasses around, or through the turbine blades.
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The VGT parameter displays data related to the position/orientation of these vanes in the turbhocharger. A value of 0% indicates that the vanes are in the maximum bypass position while at 100% the vanes redirect as much exhaust gas as possible to build boost.
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VGT Control displays the following information for one or both turbos depending on vehicle configuration:

Wastegate Control

The wastegate allows exhaust gas to bypass the turbo as boost builds to prevent excessive pressure.
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This parameter reports the following information for electronic wastegate systems (one or two depending on the vehicle configuration):

Charge Air Cooler Temperature (CACT)

This parameter reports the temperature of the intercoolerair charge on turbocharged vehicles with up to four sensors:

The SAE/OBDII standard does not specify a default mapping for these datapoints so you may need to refer to the factory manual for your vehicle to determine sensor/measurement locations.

Datapoint

Description

Emissions Control

Commanded EGR

How open the EGR valve should be as requsted by the engine computer (0% fully closed, 100% fully open)

EGR Error

The percent difference between the commanded EGR opening and the actual opening of the EGR valve.
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​Special Note:If commanded EGR is 0%, EGR error will read:

Commanded Diesel Intake Air Flow Control

Also referred to as EGR Throttle.
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Some newer diesels may employee a throttle plate to generate an intake vacuum under some conditions for the purpose of introducing EGR gasses to reduce emissions.
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This datapoint displays (if supported by the vehicle):

Exhaust Gas Recirculation Temperature

This parameter reports up to four EGR temperature values:

EVAP System Vapor Pressure

Gauge pressure of the EVAP system measured from either a sensor in the fuel tank or evap system line
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See your factory manual or a parts diagram for sensor location.

Absolute Evap System Vapor Pressure

Absolute pressure of the EVAP system measured from either a sensor in the fuel tank or evap system line (see your factory manual for vehicle specific measurement point)
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This is an absolute pressure measurement, a value of roughly 14.7 psi or 101.3 kPa indicates 0 gauge pressure relative to outside ambient conditions

Commanded Evaporative Purge

EVAPpurge flow rate requested by the engine computer

Catalyst Temperature

Temperature of the catalytic converter.

Diesel Aftertreatment Status

The Diesel Particulate Filter is used for trapping soot and reducing exhaust emissions on diesel vehicles. As soot accumulates, the filter will become "clogged" and the pressure drop across the filter will increase (see 'Diesel Particulate Filter'). When the filter reaches a set criteria it must be 'regenerated' - the soot is burned off through various methods so that the filter can be used again.
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DPF Regeneration can be:

NOx adsorbtion involves the use of various substances in the exhaust to 'trap' Nitrous Oxide - unlike with SCR there is no consumable fluid that needs to be topped up, but as the NOx 'trap' reaches capacity it must be regenerated. NOx adsorber regeneration involves exposing the 'trap' to a reductant such as fuel or hydrogen which reacts with the NOx to produce N2 and water. Over time SOx will also build up in the NOx adsorbtion system which requires a high temperature 'desulferization' process to restore the system to operating conditions.
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This is a hybrid datapoint capable of display the following (if supported by your vehicle):

Diesel Exhaust Fluid Sensor Data

This parameter will display the followng information (as supported by the vehicle):

Diesel Particulate Filter (DPF)

This parameter reports up to three separate datapoints:

An increase in differential pressure indicates that soot is accumulating in the filter, possibly indicative of an upcoming regeneration event
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Bank 1 vs 2 indicate the 'side' of the engine - bank #1 will be on the same 'side' of the engine as cylinder #1

Diesel Particulate Filter (DPF) Temperature

This parameter reports up to two datapoints for the particulate filter on each exhaust bank:

Bank 1 vs 2 indicate the 'side' of the engine - bank #1 will be on the same 'side' of the engine as cylinder #1

NOx Sensor

This hybrid parameter reports the NOx concentration levels in ppm of the following sensors (if supported):

Bank # indicates the 'side' of the engine for this exhaust - bank #1 is on the same side of the engine as cylinder #1
Sensor number indicates whether the sensor is situated before (#1) or after (#2) the NOx adsorbtion system

NOx Control System

This hybrid parameter reports the following data on the NOx adsorptionsystem (as supported by the vehicle):

NOx Sensor Corrected Data

NOx concentration in PPM including learned adjustments and offsets.

NOx NTE Control Area Status

The NOx "not to exceed control area" is a range of engine operation (speed and load) in which emissions are sampled and tested vs governmental NOx limits.
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In addition, automakers may petition the governing body for special vehicle specific exemptions for engine operation envelopes that may normally fall within the NTE test range, but that they believe should not apply. If this exception is granted a 'carve-out area' of the engine operating envelope may be defined, in which NTE limits do not apply for this specific vehicle.
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This parameter displays (as supported by the vehicle):

PM Sensor Bank 1 & 2

This parameter reports the following data (as supported by the vehicle) for banks 1 & 2:

Particulate Matter (PM) Sensor

The soot concentration as measured by the particulate matter sensors on banks 1 & 2 - displayed in mg/m3

PM NTE Control Area Status

The PM "not to exceed control area" is a range of engine operation (speed and load) in which emissions are sampled and tested vs governmental particulate matter emission limits.
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In addition, automakers may petition the governing body for special vehicle specific exemptions for engine operation envelopes that may normally fall within the NTE test range, but that they believe should not apply. If this exception is granted a 'carve-out area' of the engine operating envelope may be defined, in which NTE limits do not apply for this specific vehicle.
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This parameter displays (as supported by the vehicle):

SCR Inducement System

Selective Catalytic Reduction is used on diesel engines to reduce the amount of NOx in the exhaust using a catalyst and reductant/reagent (often urea or ammonia)
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Inducement refers to strategies employed by the vehicle to alert drivers that there is an issue with the SCR system requiring their attention - depending on the vehicle this may be a dash light, cluster message, or functional restriction (torque reduction/limp mode, speed limiter, etc)
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SCR inducement will be triggered by one or more of the following:

This paramter will report current SCR inducement status (on or off) as well as the reasons for activation. Additionally it will show whether any of the above have occurred during the the last:

Depending on the vehicle it may also report the total distance traveled during each 10,000 km block above with the inducement system active

NOx Warning And Inducement System

This parameter displays information on warning/inducement levels - for more information on inducements see SCR Induce System.
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Warning/inducement levels are broken down in to three levels:

Each level will report one of the four following statuses:

This parameter will also report (as supported):

Engine Run Time for AECD

An "Emissions Increasing Auxiliary Emissions Control Device" (AECD) is a vehicle system that has the ability to disable certain components of the vehicle's emissions control equipment. As opposed to a "defeat device", stock AECDs are permitted under regulation, but their operation and justification for use must be demonstrated to the governing body (e.g. EPA).
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Example of applications for AECDs include:

This datapoint displays the total time (in seconds) during which each AECD was active. This parameter does not provide information regarding the purpose or operation of each AECD - only the device # is listed, a factory manual may be required for more AECD specific information.
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Each listed AECD may display one or two timers:

These timers can not be reset by a scan tool or by disconnecting the battery