OBDII Parameters (Explanation)

[pangster]

The below list will explain what various OBDII Parameters represent (note: that the parameters available for display is dependant on ECU type and OBDII software used) - but a lot of the common ones are listed (and are probably self explanatory anyway! lol!!) and depending on software the units they are being measured in maybe slightly differently i.e. you often get the option of choosing 'metric' or 'English' measurements.

Air Flow Rate From MAF: Indicates the airflow rate as measured by the mass air flow sensor.

Absolute Load Value: Is the normalized value of air mass per intake stroke displayed as a percent.

Absolute Throttle Position:The absolute throttle position (not the relative or learned) throttle position. Usually above 0% at idle and less than 100% at full throttle. (I've noticed on my car that at idle it sits around 10% and at WOT it's currently 82% - although some have logged 95% before - it will NEVER read 100% so don't worry if you don't get 100% on WOT! lol!)

Ambient Air Temperature: Displays the ambient air temperature.

Barometric Pressure: Barometric pressure normally obtained from a dedicated barometric sensor. Note some whether services report barometric pressure adjusted to sea level. In these cases, the reported value may not match the displayed value.

Calculated Load Value: Indicates a percentage of peak available torque. Reaches 100% at wide open throttle at any altitude or RPM for both naturally aspirated and boosted engines.

Catalyst Temp Bank X – Sensor X (up to 4): Displays the catalyst substrate temperature.

Commanded EGR: Display 0% when the EGR is commanded off, 100% when the EGR system is commanded on, and if the EGR is duty cycled somewhere between 0% and 100%.

Commanded Equivalence Ratio: Fuel systems that use conventional oxygen sensor displays the commanded open loop equivalence ratio while the system is in open loop. Should report 100% when in closed loop fuel. To obtain the actual air/fuel ratio being commanded, multiply the stoichiometric A/F ratio by the equivalence ratio. For example, gasoline, stoichiometric is 14.64:1 ratio. If the fuel control system was command an equivalence ratio of 0.95, the commanded A/F ratio to the engine would be 14.64 * 0.95 = 13.9 A/F.

Commanded Evaporative Purge: Displays 0% when no purge is commanded and 100% at the maximum commanded purge position/flow.

Commanded Throttle Actuator: Displays 0% when the throttle is commanded closed and 100% when the throttle commanded open.

Control Module Voltage: Power input to the control module. Normally the battery voltage, less any voltage drop between the battery and the control module.

Distance Since DTCs Cleared: Distance accumulated since DTCs where cleared with a scan tool.

Distance Traveled While MIL On: Accumulates the vehicle distance traveled while the MIL light is illuminated.

Engine Coolant Temp: Engine coolant temperature derived from an engine coolant temperature sensor or a cylinder head temperature sensor.

Engine RPM: Displays the current engine revolutions per minute value.

EGR Error: Error as percent of actual commanded EGR. Negative percent is less than commanded and positive is more than commanded.

Evap System Vapor Pressure: Evaporative system vapor pressure normally obtained from a sensor located in the fuel tank.

Fuel Level Input: Indicates the nominal fuel tank liquid fill capacity as a percent of maximum.

Fuel Rail Pressure: Displays the fuel rail pressure at the engine when the reading is referenced to atmosphere (gauge pressure).

Fuel Rail Pressure Rel Manifold: Displays the fuel rail pressure referenced to the manifold vacuum (relative pressure).

Ignition Timing Advance: Ignition timing advance for #1 cylinder (not including mechanical advance).

Intake Manifold Pressure: Indicates the manifold pressure derived from a Manifold Absolute Pressure sensor.

Long Term Fuel Trim (Bank1, Bank2): Indicates the correction being used by the fuel control system in both open and closed loop modes of operation.

O2 Sensor: Indicates the voltage for conventional 0 to 1V oxygen sensors. O2 sensors with a different full-scale voltage shall be normalized to this range or, if a wide range sensor, may use the wide range parameters instead. If your car has multiple O2 sensors then you may have more than one reading for this i.e. pre and post cat.

Short Term Fuel Trim (Bank1, Bank2): Indicates the correction being used by the closed loop fuel algorithm. If the fuel system is open loop, 0% correction should be reported.

Time Since Engine Start: Shall increment the time since the engine was started while the engine is running.

Vehicle Speed: Displays the vehicle road speed.

There are other parameters too - i.e. ME7 engines support Boost etc so this is not an exhaustive list by any means - but should give you an idea of what you're looking at! lol!

[Niles]

oh me brain hurts!! lol

[pangster]

oh me brain hurts!! lol

lol! - it hurts more when you're trying to work out everything you're looking at!

[Filterlab]

Some quality and undoubtedly useful information there mate, one thing though, what's a/the DTC?

Distance Since DTCs Cleared: Distance accumulated since DTCs where cleared with a scan tool.

[Yosser]

DTC = Diagnostic Trouble Code

so thats any stored fault codes that the car has.

[pangster]

Some quality and undoubtedly useful information there mate, one thing though, what's a/the DTC?

what Yosser said! lol!

[Filterlab]

Ahhh, I just didn't know that acronym. I've always simply said "codes".

[pangster]

Ahhh, I just didn't know that acronym. I've always simply said "codes".

this is quite a useful link r.e. jargon and acronyms:

http://www.obdii.com/acronyms.html

HTH

[BruceT]

Ive just noticed today that the engine check light does come on nor the service light when the ignition is first turned on.

So will be interesting to see if there both on and what errors I have if any as ive drove for 1000 miles since owning the car and its been ok - lol

[CONDYBOY]

Anybody know the pinouts or have a wiring diagram for a volvo v40 1.9td bosch edc15c3 ecu?