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.

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.

Note: It is not the same as the battery voltage.

The remaining total charge percentage in the hybrid battery pack. 

Note: Standard OBD2 doesn't show individual cell data.

The following parameters of Hybrid Electronic Vehicle systems will show in your OBD2 Scanner:

• HEV Charging State: Charge Sustaining Mode (CSM), a control system that maintains a constant State of Charge, or on a Charge Depletion Mode (CDM), a control system that targets lower current valued SOCs. 
• Non-PHEVs permanent Charge Sustaining Mode
• HEV Battery voltage that ranges from 0V to 1024V
• HEV Battery Current ranges from (- value means it is at charging state) -3300 Amps to 3300 Amps.

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.

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. 

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.

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. 

It is a composite data point that is capable of providing details of the following vehicle system status:

• On or Off Status of Power Take Off and Glow Plug Lamp
• Park/Neutral or Drive/Reverse Status of  Automatic Transmission
• Neutral/Clutch In or In Gear Status of Manual Transmission
• 1 to 15 Status of Recommended Transmission Gear

It is measured by sensors which are installed on the following systems to guard the components from critical overheating:

• Turbo Charger
• Catalytic Converter
• Diesel Particulate Filter
• Components of the NOX reduction system

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.

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.

It is a parameter report which measures the total run time of the following engine status:

• Engine Run Time in Seconds
• Engine Idle Time In Seconds
• Engine Run Time when PTO is engaged

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.

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.

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.

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.

This data point shows the status of two fuel systems which runs in Open and Closed Loop Mode.

• Open Loop Modes means the engine computer uses pre-programmed air: fuel ratios to decide the amount of fuel to be injected.
• Closed Loop Mode means that the ECM uses the O2 sensor feedback to adjust the air: fuel ratio to prevent too much air or gas condition.

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.

Command Equivalence Ratio (CER), also known as lambda, determines the air and fuel ratio requested by the ECM. 

Wide Range O2 Sensored Vehicles

• CER is displayed in both open and closed loop mode.

Conventional O2 Sensored Vehicles

• CER is displayed in open loop mode.
• 1.0 display in closed loop mode

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 (IAT) is the value of the temperature that travels through the engine cylinders. There are 3 IAT sensors in a vehicle with different functions:

• To measure the air that enters the engine.
• To measure the climate control system of a vehicle.
• To measure the ambient air temperature.

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. 

• Running Engine: 18 - 20 "Hg intake manifold vacuum
• Idle Engine: 0 - 20 20 "Hg intake manifold vacuum

Fuel pressure value.

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

The ethanol/alcohol content as measured by the engine computer in percentage.

For example an E85 blend would show 85% for alcohol fuel percentage

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

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.

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

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

• Fuel pressure control: Closed or open loop control
• Fuel injection quantity: Closed or open loop control
• Fuel injection timing: Closed or open loop control
• Idle fuel balance/contribution: Closed or open loop control

Closed loop indicates the system is using sensor feedback for fine tuning.

Note: Systems 1 & 2 refer to two separate fuel systems - system 2 may not be in use on most vehicles

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

1. Commanded rail pressure
2. Actual rail pressure
3. Temperature

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

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:

1. Commanded Control Pressure Rail A
2. Actual Pressure Rail A
3. Commanded Control Pressure Rail B
4. Actual Pressure Rail B

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

1. ECM commanded boost pressure
2. Actual boost pressure

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.

This parameter will also provide feedback on the operating mode of the boost control system, possible states are:

1. Open Loop - No sensor feedback used, no faults present
2. Closed Loop - Using sensor feedback, no faults present
3. Fault Present - Boost data unreliable

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

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

1. Compressor inlet temperature - Air charge temperature before the turbo
2. Compressor outlet temperature - Air charge temperature at the turbo outlet - this value should be much higher
3. Turbine inlet temperature - Exhaust temperature pre-turbo
4. Turbine outlet temperature - Exhaust temperature post-turbo

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

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

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:

1. Commanded VGT Position - Vane position requested by the vehicle
2. Actual VGT Vane Position
3. VGT Control Status: Closed or Open Loop (using sensor feedback or not) without system faults or in a Fault State (VGT position data is unreliable)

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):

1. Commanded wastegate position as requested by the controller - 0% represents fully closed (all exhaust routed through the turbo) and 100% indicates maximum diversion around the turbine section.
2. Actual wastegate position - 0% to 100%

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

1. Bank 1 Sensor 1
2. Bank 1 Sensor 2
3. Bank 2 Sensor 1
4. Bank 2 Sensor 2

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

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:

• 0% if actual EGR is also 0%

• 99.2% if actual EGR is anything other than 0% - this indicates "undefined" or not applicable

  
  

  EGR error is calculated as (actual - commanded)/commandedA commanded value of 0% gives (0-0)/0 = 0% With any other 'commanded' value the calculation becomes (actual-0)/0 which is undefined

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):

1. The commanded (closed to 100% open) position of the intake air flow throttle plate
2. The actual position of the EGR throttle
3. Commanded position of a second EGR throttle if fitted
4. Actual position of secondary EGR throttle

This parameter reports up to four EGR temperature values:

1. EGRTA - Bank 1 Pre-Cooler
2. EGRTB - Bank 1 Post-Cooler
3. EGRTC - Bank 2 Pre-Cooler
4. EGRTD - Bank 2 Post-Cooler

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 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

EVAP purge flow rate requested by the engine computer

• 0% fully closed
• 100% maximum

Temperature of the catalytic converter.

• Bank # indicates the 'side' of the engine (typically bank 1 will be on the same side as cylinder #1)
• Sensor # indicates whether the sensor is pre (#1) or post (#2) cat

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:

1. Passive - using standard exhaust temperature while driving
2. Active - using fuel injection to increase the exhaust temperature
3. Forced - triggered using a factory scan tool before the regen criteria of the vehicle is met

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 absorber 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 adsorption system which requires a high temperature 'desulfurization' process to restore the system to operating conditions.

This is a hybrid data point capable of display the following (if supported by your vehicle):

1. Current DPF Regeneration Status: Active/Not Active
2. Current DPF Regeneration Type: Passive/Active
3. NOx Absorber Regen Status: Active/Not Active
4. NOx Absorber Desulfurization Status: Active/Not Active
5. Normalized Trigger for DPF Regen: The percentage until the next regen event - 0% means a regen has just completed while 100% indicates one is about to start
6. Average Time Between DPF Regens: The exponential weighted moving average time between regen events, indicating a representative value over the last 6 events
7. Average Distance Between DPF Regens: The exponential weighted moving average distance driven between regen events, indicating a representative value over the last 6 events

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

1. DEF Type: Urea too high, Urea too low, Straight diesel, Proper DEF, Sensor fault
2. DEF Concentration: Urea concentration - should display roughly 32.5% for proper DEF
3. DEF Tank Temperature
4. DEF Tank Level - Important note: tank level may not change progressively, see 'NOx Control System' above for more information

This parameter reports up to three separate data points:

1. Inlet pressure
2. Outlet pressure
3. Differential pressure across the particulate filter

An increase in differential pressure indicates that soot is accumulating in the filter, possibly indicative of an upcoming regeneration event

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

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

1. Inlet temperature
2. Outlet temperature

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

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

1. Bank 1 Sensor 1
2. Bank 1 Sensor 2
3. Bank 2 Sensor 1
4. Bank 2 Sensor 2

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 adsorption system

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

1. Average Reagent Consumption Rate - Calculated either over the previous 48 hours of engine run time or the last 15L consumed (whichever is a longer period). This value will be reported as 0 when the key is on with the engine off
2. Average Demanded Consumption Rate - As commanded by the ECM, calculated either over the previous 48 hours of engine run time or the last 15L consumed (whichever is a longer period). This value will be reported as 0 when the key is on with the engine off
3. Reagent Tank Level - 0 to 100%
4. Note: Depending on the vehicle, tank level might not display a progressive value between 100% and 0% as fluid is consumed - tank level may only display values at specific measurement points.
5. If a vehicle is not capable of reporting true tank level at all times, it will show the average between each discrete step when not measuring that exact level.
6. For example, consider a vehicle that is only capable of directly measuring three tank levels: full at 100%, low at 20%, empty at 0% As fluid is consumed to depletion over time this data point will report:
• 100% when full
• 60% while the actual fluid level is between 20% and 100%
• 20%
• 10% while actual level is between 0% and 20%
• 0% at empty

7. NOx Warning Indicator Time - Total engine run time in seconds since the NOx/SCR (DEF etc) warning light has activated on the dash. This data point will start at 0 when the NOx warning light comes on, and count up for every second of engine run time that the light is on - to a maximum of 136 years (seriously).

   Once the NOx light goes out the counter will stop increasing, and it will reset if the light comes back on or 9600 engine-hours pass without the light activating again.

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):

1. Whether vehicle is operating inside or outside the NOx control area
2. Whether the vehicle is operating inside the manufacturer exception/'carve-out' region
3. Whether the vehicle is experiencing an NTE related deficiency within the NOx operating control area

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

• Particulate matter sensor active: yes/no
• Particulate matter sensor regenerating: yes/no
• Particulate matter sensor value: 0% (clean) to 100% (regen required)

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):

1. Whether vehicle is operating inside or outside the PM control area
2. Whether the vehicle is operating inside the manufacturer exception/'carve-out' region
3. Whether the vehicle is experiencing an NTE related deficiency within the PM operating control area

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:

1. Low reagent level
2. Incorrect reagent used (e.g. water instead of DEF)
3. Abnormal reagent consumption rates
4. Excessive NOx emissions

This parameter 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:

1. 0 - 10,000 km
2. 10,000 - 20,000 km
3. 20,000 - 30,000 km
4. 30,000 - 40,000 km

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

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:

• Level 1 - Low severity, e.g. minor power/torque reduction
• Level 2 - Medium severity, e.g. significant power/torque reduction (limp mode)
• Level 3 - Severe, e.g. complete engine shut down, extreme operational limits

Each level will report one of the four following statuses:

1. Inactive
2. Enabled, but not active (triggered - but not taking effect yet)
3. Active
4. Not supported by vehicle

This parameter will also report (as supported):

1. Total engine hours using incorrect reagent
2. Total engine hours with incorrect reagent consumption rate
3. Total engine hours during which reagent dosing was interrupted (e.g. AECD)
4. Total engine hours during which there was an active DTC for incorrect EGR operation
5. Total engine hours during which there was an active DTC for incorrect NOx control equipment operation

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:

• Mitigation of engine damage during abnormal operation
• Providing maximum power/torque for emergency situations
• Ensuring continuous operation of emergency equipment

This data point 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.

Each listed AECD may display one or two timers:

• If only one timer is used:
• TIME1 will display the total engine run time during which this AECD was active
• TIME2 will display a maximum value (136 years) to indicate 'not used'
• If two timers are used:
• TIME1 will display engine run time during which an AECD was inhibiting up to 75% of emissions control performance
• TIME2 displays engine run time during which emissions control was inhibited beyond 75%

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