OBD2 standard
OBD2 (or OBDII) defines a communications protocol and a standard connecter to acquire data from passenger cars. It was required by U.S. EPA on all gasoline powered cars and light duty trucks manufactured for the U.S. after 1996 to help monitor/inspect vehicle emissions. Canada required it after 1998, and a European standard (EOBD) is also enforced.

OBD2 electrical interfaces
The OBD2 standard allows for multiple electrical interfaces, which complicates the hardware used to interface with the vehicle.  Here is a brief summary of the most popular electrical interfaces:

• ISO15765 (CAN) - Controller Area Network, a new higher speed interface, just now being implemented (This protocol is currently not supported by any ELM32x or by our software)
• ISO9141-2 used mostly by Chrysler and the European/Asian imports
• ISO14230, or KWP2000 (Keyword Protocol) shares the electrical portion of ISO9141 standard, but defines it’s own commands. (This protocol is currently not supported by the ELM323 (ISO) or by our software)
• PWM J1850-41.6 (41.6Khz Pulse Width Modulated) used mostly by Ford (supported by the ELM320 chip)
• VPW J1850-10.4 (10.4Khz Variable Pulse Width) used mostly by GM vehicles (supported by the ELM322 chip)

OBD2 Acronyms
Some additional terms you may run across in OBD2:

• CTS - Coolant Temperature Sensor, pretty self-explanatory
• DLC - Data Link Connecter, the standardized plug in the vehicle, a 16-pin trapezoidal connecter, often found under the driver side dash (U.S. EPA’s allowed DLC location GIF)
• DTC - Diagnostic Trouble Codes, an alphanumeric code indicating a specific fault reported by the OBD system
• ECM - Electronic Control Module, a vehicle computer
• ECU - Electronic Control Unit, a vehicle computer
• EGR - Exhaust Gas Recirculation, to recirculate unburnt volatiles in exhaust
• HO2S - Heated Oxygen Sensor, refers to oxygen sensors in exhaust path looking for unburnt oxygen
• ISO - International Standards Organization
• KOEO - Key On Engine Off, describes some tests without engine running, but ignition on
• KOER - Key On Engine Running, describes tests with engine running
• MAF sensor - Mass Air Flow measures amount of air being drawn into intake
• MAP sensor - Manifold Absolute Pressure, reads air pressure to adjust timing, fuel/air ratios
• MIL - Malfunction Indicator Light, indicates a trouble code has been recorded. Also referred to as the Service Engine Soon light, the Check Engine light, idiot light, etc. Usually can only be reset by an OBD2 tool (even if the condition is no longer present), will automatically fail any emissions test if lit.
• PCM - Programmable Control Module, a vehicle computer that can be reprogrammed/have values modified
• PCV - Positive Crankcase Ventilation - recirculates unburnt volatiles escaping into crankcase
• SAE - Society of Automotive Engineers
• Scantool - an OBD2 tool
• SIR - Supplemental Inflatable Restraint - airbag
• Tap Test - Gently striking the ECU housing with fingers with engine running to check for intermittent connections
• TPS - Throttle Position Sensor, monitors position of the accelerator pedal/throttle linkage
• WOT - Wide Open Throttle, pedal to the metal

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How to get better gas mileage?

With today’s high gas prices, here are some tips from OBD2 blog.

Here are simple tips:

1. Go Easy on the Pedals
2. Slow Down
3. Leave Extras at Home
4. Use Cruise Control (When Appropriate)
5. Turn off the Car, when idling at read lights
6. Check Tire Pressure
7. Replace Spark Plugs
8. Check Alignment
9. Fill Your Tank Early in the Morning - or Late at Night
10. Purchase an OBD2 CAN Scanner,  very good to check the condition of the oxygen sensor O2. Replacing near faulty O2 sensors drastically improves gas mileage and performance.

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Car Owners Can Save Hundreds of Dollars on Auto Repairs with a OBD2 scanner.

DIY, is the keyword here.

How ? You purchase a OBD2 Scan Tool  for under one hundred dollar.

Then by utilizing tips and information on online help, automotive forums and other tools. Example, you get a check engine light code (DTC) P0171 and P0174 on a Ford F-150, Some Mechanic tells you that is 100 % sure it’s the Oxygen sensor !!!

But, What it means is that the engine is running lean. There are many possible problems that may cause the air-fuel mixture to be lean: Defective or contaminated airflow sensor, intake vacuum leak, dirty fuel filter, etc. There are certain tests to be performed to find the exact cause of the problem. Common problems with Ford engines are defective airflow sensors and vacuum leaks.

So, replacing the O2 sensors for nothing may cost you up to $ 600. By using this simple and low cost obdii CAN scanner

You can save Hundreds and Hundreds Dollars. The internet is full of Forums dedicated to you our make of car and with valuable advice form users that did repair their our cars.

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Hi,

I found some new exciting software on the market for advanced obd2 diagnostics. With these programs you can read, erase and log :

anti-lock braking system (ABS OBDii)

supplementary restriant system (SRS OBD-ii)

advanced powertrain systems like electronic transmissions, CVT  (Auto OBD2)

Right now theses software packages are just available for Ford, GM and Mazda cars.

 Obd2 Enhanced Software Packages

ECU scanning has come from a long way since obd1 systems.

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Hi,

I was looking at a low cost solution for scanning codes and reading sensors data for a PC. I found the ELmscan5 compact for $ 80.00 shipping including at Carplugs.com .

I don’t think you can find something similar at a lower price.  You can find some Chinese clones on FleaBay but those are not commercial grade scanners.

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The Obd2 blog will have new features in 2009. It will be Scantool reviews, scanner tests and code readers software.

Look for this soon on Obdii Weblog.

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From: garysautotechclub (Yahoo Group) , Author : overtork187

Oxygen sensors are described as “upstream” or “downstream.”
An “upstream” sensor is located near the engine, typically in the
exhaust manifold. A “downstream” sensor is located near the catalytic
converter. Though both perform the same function – measuring the
proportion of unburned fuel and oxygen in the exhaust – the differing
data points allow the engine computer to determine whether all of the
components in the engine management and emissions systems are
properly functioning.

That means, of course, that there will always be at least two O2
sensors in any vehicle – at least those built after 1996, when the
emissions regulations requiring oxygen sensors became law.
Usually, however, there are more – often as many as four.
Any car with a V engine (V-6, V-8, etc.) will have two upstream
sensors, one for each cylinder bank. These are called the “bank 1″
and “bank 2″ sensors. Bank 1 is whichever cylinder bank has the
number one cylinder. That’s the one that fires first in the firing
order. (All cylinders on an in-line engine are bank 1.)
The number of downstream sensors varies between manufacturers and
vehicles. One will always be located downstream of the catalytic
converter, so that there is a measure of the converter’s efficiency.
But many car makers use two downstream sensors, one somewhat before
of the catalytic converter and the other after it.

Sensors are also described by the number of wires employed: three,
four, or five. Because O2 sensors don’t function properly until they
reach an operating temperature of about 600ºF., modern practice is to
electrically heat the sensor so that it functions as soon as the
engine starts. How that is accomplished determines whether three or
four wires are used. The latest technology in O2 sensors,
the “wideband” sensor, uses five wires. You must replace a sensor
with one that uses the same number of wires as the original.
Sensors are either “universal” or “direct fit.” Universal sensors are
designed to fit multiple vehicles using the same sensor “bulb,” the
part that sticks into the exhaust. But, universal sensors do not come
ready to install. The electrical connector will have to be assembled
first. In contrast, a direct fit sensor is ready to install right out
of the box and simply plugs into the existing wiring.

Which sensor do you replace?

A scan tool or code reader will retrieve the diagnostic trouble code
set as the result of an O2 sensor malfunction. Trouble codes are
specific to the sensor, so the trouble code will effectively
designate the sensor which set the code.

Check out this Obd2 Scan Tool for retrieving codes

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Using a car scanner or scan tool can be a big step in the air quality that we breathe. Why? Because you can see if an oxygen sensor in your car is starting to be faulty. A defective oxygen sensor can trick your car computer’s to run the car too rich or too poor. Then you can smell unburnt gas coming out of exhaust pipe.Using a scan tool like the Elmscan5 can make you locate the faulty sensor. Of course you need also a desktop computer or laptop for reading the scan tool’s results. A good scanner will make you do live results with the car running on the road. This is the best way of testing various sensors or fuel injectors on you automobile. A footnote:the obd2 system is designed to monitor the emissions performance of the engine.You read the oxygen sensor or O2 sensor results like this: the voltage output of the O2 sensor should read minimum 0.1Volts (lean) and maximum 0.9 Volts (rich). A good oxygen sensor should produce an oscillating waveform at idle that makes voltage transitions between 0.1 and 0.9 Volts. A bad sensor could be always stuck at 0.45 Volts . If you look at the output of an oxygen sensor with an oscilloscope with a good sensor, you will see a oscillating waveform (sine wave).With a very good Obd2 scan tool, you see see the graph of the output of the sensor like you were looking at the monitor of an oscilloscope. You must also see the voltage reading of all sensors including the O2 sensors with the smallest delay possible.

In conclusion, if you monitor your car’s emissions performance of the engine. You can replace faulty or near faulty O2 sensors. You will gain performance of the engine because a car run much better with new oxygen sensor. You will burn less full and you will pollute less in our precious atmosphere.

Check it out: http://www.carplugs.com/obd2usb.html

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What is the difference between OBDii, OBD-II, OBD ii and OBD2?

Answer: None, It seems that different corporations used different terminology. The items like connectors, cables or scan tools have no standard of writing except of the OBDii connector should be called J1962.

If you look at some search results on MSN, Google, Yahoo or ASK, the most popular one is OBDii. Personally, I like more the OBD2 term.

For OBDii Connectors, OBDii Cables OR Scan Tools Go to www.carplugs.com

Regards,

Mario I.

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Welcome to OBD2 Weblog.

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