A Guide for Live Data
Purpose
To help you identify OBD2 data point descriptions for Live Data.
Data Points and Descriptions
Note: Some Data Points vary based on a vehicle's make and model. To know more about the data points, refer to your vehicle's support manual.
Vehicle Operation Parameters
Fuel & Air Data
Emissions Control Equipment Information
| Parameter Identifiers (PIDs) | Description |
|---|---|
| Vehicle Operation | |
| Engine RPM | Engine Revolutions Per Minute |
| Vehicle Speed | Speed of your Vehicle |
| Engine Coolant Temperature | Coolant temperature is usually measured by a coolant temperature sensor confined to the vehicle's engine that feeds information in the form of electrical current to the engine control unit or ECU. |
| Engine Oil Temperature | Oil temperature is usually measured through thermocouples, thermistors or RTD sensors. It would be best to control oil temperature because of its specific working range. |
| Ambient Air Temperature | Ambient Air Temperature is the temperature outside the passenger compartment and measured by a thermometric sensor mounted inside or near the front of the vehicle's bumper. |
| Barometric Pressure | Barometric Pressure, also known as Atmospheric Pressure, is usually measured by a BARO sensor. The PCM uses the sensor's information to adjust fuel trim and engine timing. Note: The average vehicle barometric pressure is 14.7 PSI at sea level. |
| Accelerator Pedal Position | Pedal positions on the driver's side of your car floor control your vehicle's power and speed, which are the accelerator, the foot brake and the clutch. Each pedal is measured and controlled by individual sensors. |
| Relative Accelerator Pedal Position | A sensor evaluates the accelerator pedal position based on the output voltages to the pedal position. The vehicle may not always show 100% when placed on the floor. Note: Sensor may show the average value of the multiple position sensors depending on the vehicle. |
| Commanded Throttle Actuator | The throttle position requested by the ECM based on accelerator pedal position. |
| Relative Throttle Position | The Relative Throttle position compares the throttle position and the learned closed position. Carbon builds up over time, and other factors may affect throttle behavior. Adjustments to the throttle position are made to compensate for the changes in the previous throttle position. |
| Absolute Throttle Position | Also known as the actual position of the throttle and measured through its opening, which is 0% if completely closed or 100% if it is fully open. |
| Control Module Voltage |
It is the voltage supplied to the engine control unit whose value is close enough to the voltage when the vehicle is running.
Note: It is not the same as the battery voltage. |
| Hybrid Battery Pack Remaining Life |
The remaining total charge percentage in the hybrid battery pack. Note: Standard OBD2 doesn't show individual cell data. |
| Hybrid/EV Vehicle System Status |
The following parameters of Hybrid Electronic Vehicle systems will show in your OBD2 Scanner:
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| Calculated Engine Load Value | It is the calculated MAF sensor value of the current airflow in the engine divided by the peak airflow. Note: The altitude corrects peak airflow. |
| Absolute Load Value | It is the normalized percentage value of air mass per intake stroke. It is calculated by dividing air mass per intake stroke (g) by air mass per intake stroke at 100% throttle. Note: Values differ when your vehicle is idle, parking or without accessories. |
| Driver's Demand Engine - Percent Torque | It is the maximum available engine torque percentage value based on accelerator pedal position, cruise control, and transmission requested by the ECM. Note: Other external factors such as traction control and abs won't affect the values. |
| Actual Engine - Percent Torque | It is also known as Indicated Torque, whose parameters are shown as the current percentage of total available engine torque, net brake torque and friction torque required to run the engine without load. |
| Engine Friction - Percent Torque | It is the maximum engine torque percentage value required to run a 'fully equipped' no load engine, including internal engine components, fuel, water pump, air intake, alternator, exhaust and emission control equipment. |
| Engine Reference Torque | It is a torque rating of the engine considered as 100% value for Actual Engine Percentage Torque and other parameters with percentage torque outputs. Note: Its value is constant and never changes over time. |
| Engine Percent Torque Data | A parameter used when changes in vehicle conditions can cause torque reference to change. |
| Auxiliary Input/Output | It is a composite data point that is capable of providing details of the following vehicle system status:
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| Exhaust Gas Temperature (EGT) | It is measured by sensors which are installed on the following systems to guard the components from critical overheating:
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| Engine Exhaust Flow Rate | It is the flow rate of the air and fuel mixture ignited using a spark plug. To calculate engine flow rate, exhaust temperature, volumetric efficiency, engine size and flywheel RPM are required. |
| Exhaust Pressure | It is displayed as an absolute pressure value when the engine is on and roughly ambient atmospheric value when it is off. Note: Report data from one or two exhausts depends on vehicle configuration. |
| Manifold Surface Temperature | Temperature value of the exhaust manifold's outer surface. |
| Timing Advance for #1 cylinder | It is a manufacturer-specific timing regarding the angle of the top dead center (TDC) and the time before the #1 cylinder should fire. Note: A positive value means delayed spark plug firing, and a negative value means spark plug fires before #1 cylinder reaches the top. |
| Engine Run Time | It is a parameter report which measures the total run time of the following engine status:
|
| Run Time Since Engine Start | Total run time in seconds since the engine starts ignition. |
| Time Run with MIL On | Total Engine run time since the activation of the check engine light after a code is thrown. Note: This parameter is different from total elapsed time. For example, when you have been driving your car for 3 months and your check engine light came on a month ago, the value of this parameter will start when the check engine light started to occur. |
| Distance Traveled while MIL is Activated | The total distance your vehicle has travelled since the check engine light activation. Note: This parameter will reset once codes are cleared, or your vehicle's battery is disconnected. |
| Time since Trouble Codes Cleared | Total Engine run time since the codes were cleared by your OBD2 Scan tool or the battery is disconnected. |
| Distance Traveled Since Codes Cleared | Total distance covered of the vehicle since the codes were cleared by the OBD2 Scan tool or battery is disconnected. Note: This parameter will not reset even if clearing non-engine codes are done. |
| Warm-ups Since Codes Cleared | The total number of engine warm-up cycles after clearing codes or disconnecting the battery. Note: A warm-up cycle is achieved when the coolant temperature reaches at least 40 °F after startup and reaches at least 170 °F. |
| Data Point | Description |
|---|---|
| Fuel & Air | |
| Fuel System Status | This data point shows the status of two fuel systems which runs in Open and Closed Loop Mode.
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| Oxygen Sensor Voltage | This sensor measures the generated O2 voltage within the vehicle system. The generated voltage should be from 0.1 V to 0.9 V. If the reading is within this range, your O2 sensor is working properly. |
| Oxygen Sensor Equivalence Ratio | Also known as the Lambda sensor. In closed loop mode, this sensor will inform the engine to adjust the fuel and air mixture. While in open loop mode, the engine won't listen to it. |
| Oxygen Sensor Current | This is the current that flows within the Oxygen sensor, which means that if the value is 0 mA, it has a well-balanced air: fuel ratio. If it has a positive current, it has a lean mixture (more air than required), and if it is a negative current, it has a rich mixture (less air than needed). |
| Short Term Fuel Trim | It involves on-the-spot changes the computer makes in response to the oxygen sensor. If the sensor reads a lean mixture, the computer compensates it by adding fuel, and if the oxygen sensor reads a rich mixture, the computer leans the fuel mixture out. |
| Long Term Fuel Trim | The percentage of ECM adjustments calculates the quantity of fuel to be injected into the cylinders to compensate for the changes over a longer period. Note: Changes in Long Term Fuel Trim only take seconds to update, and it is permanently stored in the ECM memory. |
| Commanded Equivalence Ratio | Command Equivalence Ratio (CER), also known as lambda, determines the air and fuel ratio requested by the ECM. Wide Range O2 Sensored Vehicles
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| Mass Air Flow Rate | Mass airflow rate is the value measured by a vehicle MAF sensor which should be within the range from 2 to 7 g/s at idle and rise to between 15 to 25 g/s at 2500 rpm. Note: If you want to ensure your vehicle's airflow rate, refer to your manufacturer's specifications. |
| Intake Air Temperature | Intake Air Temperature (IAT) is the value of the temperature that travels through the engine cylinders. There are 3 IAT sensors in a vehicle with different functions:
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| Intake Manifold Absolute Pressure | It is the Manifold Absolute Pressure (MAP) Sensor inside the intake. It is measured by a MAP Sensor which works with the intake air pressure to determine the amount of air and fuel to ignite the cylinders.
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| Fuel Pressure (Gauge) | Fuel pressure value. 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 atmospheric/ambient pressure reading) |
| Fuel Rail Pressure (Absolute) | Pressure in the fuel rail displayed as an absolute pressure value - when the fuel rail is not pressurized this data point 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. 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 Engine fuel rate is calculated by the ECM using the volume of fuel used during the last 1000 ms 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. This data point 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. 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):
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:
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| 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. The ICP sensor monitors the pressure on the oil side of the fuel system, depending on the vehicle this parameter will display:
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| Boost Pressure Control | Depending on the vehicle this parameter will show the following for one or two turbochargers:
This parameter will also provide feedback on the operating mode of the boost control system, possible states are:
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| Turbocharger RPM | Measured turbine RPM of one or both turbos depending on vehicle configuration. Note: This data point 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:
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| Turbocharger Compressor Inlet Pressure Sensor | Pressure measured at the turbocharger inlet, for either one or two turbos depending on vehicle configuration This is an absolute pressure value, a value of roughly 14.7 psi / 101.3 kPa indicates atmospheric 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. The VGT parameter displays data related to the position/orientation of these vanes in the turbocharger. 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. VGT Control displays the following information for one or both turbos depending on vehicle configuration:
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| Wastegate Control | The wastegate allows exhaust gas to bypass the turbo as boost builds to prevent excessive pressure. This parameter reports the following information for electronic wastegate systems (one or two depending on the vehicle configuration):
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| Charge Air Cooler Temperature (CACT) | This parameter reports the temperature of the intercooler air charge on turbocharged vehicles with up to four sensors:
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| Data Point | Description |
|---|---|
| Emissions Control | |
| Commanded EGR | How open the EGR valve should be as requested 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. Special Note: If commanded EGR is 0%, EGR error will read:
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| Commanded Diesel Intake Air Flow Control | Also referred to as EGR Throttle. 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. This data point displays (if supported by the vehicle):
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| Exhaust Gas Recirculation Temperature | This parameter reports up to four EGR temperature values:
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| EVAP System Vapor Pressure | Gauge pressure of the EVAP system measured from either a sensor in the fuel tank or evap system line 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) 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 | EVAP purge flow rate requested by the engine computer
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| Catalyst Temperature | Temperature of the catalytic converter.
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| 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. DPF Regeneration can be:
This is a hybrid data point capable of display the following (if supported by your vehicle):
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| Diesel Exhaust Fluid Sensor Data | This parameter will display the following information (as supported by the vehicle):
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| Diesel Particulate Filter (DPF) | This parameter reports up to three separate data points:
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 data points for the particulate filter on each exhaust bank:
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| NOx Sensor | This hybrid parameter reports the NOx concentration levels in ppm of the following sensors (if supported):
Sensor number indicates whether the sensor is situated before (#1) or after (#2) the NOx adsorption system |
| NOx Control System | This hybrid parameter reports the following data on the NOx adsorption system (as supported by the vehicle):
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| 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. 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. This parameter displays (as supported by the vehicle):
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| PM Sensor Bank 1 & 2 | This parameter reports the following data (as supported by the vehicle) for banks 1 & 2:
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| 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. 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. This parameter displays (as supported by the vehicle):
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| 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) 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.) SCR inducement will be triggered by one or more of the following:
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| NOx Warning And Inducement System | This parameter displays information on warning/inducement levels - for more information on inducements see SCR Induce System. Warning/inducement levels are broken down in to three levels:
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| 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). Example of applications for AECDs include:
Each listed AECD may display one or two timers:
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