What Is the OBD II System on My Car?

What is the OBDII System on my car?
Experienced mechanics share their insights in answering this question :
OBD II is an abbreviation of on board diagnostic system generation two. The system was brought into service in the vehicles of model year 1996. The system was put into all vehicles to monitor the operation and control the engine and powertrain systems to meet federal and international regulations.

The computer control systems on vehicles with OBD II have the capability to allow anyone that has a scanner with the same connector to access information in the vehicle’s computer. The connector for this system is standardized for all vehicles with OBD II. The information obtained from the OBD II system using a scanner is all dependant on what information the manufacturer decides to release. A factory scanner can access all the capabilities a manufacturer releases and a generic scanner is limited to only code retrieval, but can sometimes have the capabilities of a factory scanner depending on the scanner being used.

The data that can be retrieved using a scanner is the input to the computer from the sensors in the system and the computer output to operate components after the computer has processed the input information. If the computer gets bad data or components fail, the computer will store an OBD II code in its memory. The code may be a generic code or a manufacturer specific code. The code is retrieved using the OBD II connector and a scanner. The code can be used to diagnose the vehicle problem that caused the code.

The OBD II system has a set of codes called generic codes that are used to give the general failure of a component or sensor system. The code may not give an exact component or sensor failure. This will be dependent on the manufacturer release and code meaning. The manufacturer may have additional codes they would use in addition to the OBD II generic code, called manufacturer specific codes. These codes will narrow down the diagnostics for the user further to help in diagnosis.

The OBD II system is to help in diagnosing a vehicle problem. The system was not designed to give an absolute answer to the source of the problem, but a general area for a person to look at when trying to repair the vehicle. This is why each manufacturer has a set of pinpoint tests for each code the system gives out. Some codes may or may not be used by all manufacturers. The pinpoint tests are different for all manufacturers for the same codes. This is why it is important to use the OBD II system as a guide to a repair and not just replace a part immediately. This was not its intention. It was intended to be used by a mechanic as a tool to help in diagnosing a problem with your vehicle. Today, with the advent of generic scanners it has been used as a general indication of what part to change. This has caused a large amount of repairs to be incorrect since many consumers perceive the code from the OBD II system as an indicator of what part to change. The OBD II system needs to be used again as it was intended. It is another tool to be used to help diagnose a system problem, but not a guide for the consumer to decide what parts to replace.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

What is OBD II? OBD II is an acronym for On-Board Diagnostic II, the second generation of on-board self-diagnostic equipment requirements for light- and medium-duty California vehicles.
OBD stands for On-Board Diagnostics and is a computer system inside of a vehicle that tracks and regulates a car`s performance. This on-board computer system collects information from the network of sensors inside the vehicle, which the system can then use to regulate car systems or alert the user to problems.
1996 or newer model year vehicle sold in the United States

United States legislation requires all cars and light trucks model year (MY) 1996 and newer to be OBD2 compliant.

A “2” refers to fuel or air metering injection system issues, such as a fuel injector problem. A “3” indicates an ignition-related problem, such as an engine misfire. A “4”refers to emissions system problems, like a catalytic converter efficiency issue.
OBD-I vs. OBD-II. The central difference between first generation OBD systems and OBD-II is that OBD-II systems are now homogenized into the vehicle itself. Unlike OBD-I, wherein diagnostic systems were externally linked to a vehicle`s console.
These OBD codes were standardized using SAE J2012 and ISO 15031-6 standards which, to our knowledge, contain about 11 000 definitions in the most recent version. Below you will find a list of the most commonly used codes. Our software contains all of the 11 000 codes.
The OBD-II port is usually located under the dashboard, beneath the steering wheel column (1 – 3 in the diagram below). If not located beneath the steering column, look for the port in the areas indicated by numbers 4 – 9.
There are two tools that help you properly diagnose your vehicle`s OBD-II codes: code readers and scan tools. An OBD-II code reader can read, display, and even clear DTCs and reset the check engine light on your vehicle. It`s a convenient tool for car owners that want to perform these basic functions.
There will be a note on a sticker or nameplate under the hood stating “OBD II compliant” or “OBD II Certified”.
Do OBD2 readers work on all cars? Most OBD2 scanners and car code readers do not work on all cars. If you are looking for an OBD2 scanner or car code reader, you should check if it works with your particular make and model before buying it.
It`s completely safe to leave an OBD2 scanner tool plugged in while driving. In fact, it`s important to have your car running while you diagnose an engine code to avoid damaging the scanning software.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

I put the wrong key in my car and a few weeks later my car just shut down and it will not start I believe it’s the computer but…
ANSWER : Hi there. What had happened is the wrong key set the security to the vehicle. This is to prevent the vehicle from starting with the wrong keys. Try removing the battery cables (+) and (-) for 13 minutes. During that time, put the original key in the ignition and turn it on. Activate everything in the car even though there is no power. Then remove the key and hook up the battery cables. The computer should have reset and reset the security. If the security is still being tripped, then I recommend seeking out a professional, such as one from Your Mechanic, to help you

Replaced alternator on car 2 times each time shows it’s charging 14v let car run for a little bit then test drive and car voltage
ANSWER : There are reports that the replacement alternators will not communicate with the engine computer and will not charge correctly. I recommend using only the manufacturer approved replacement part. It can be new or remanufactured but approved for use in the vehicle. Some lower cost alternators on the aftermarket will have charging problems since they will not communicate with the ECM on the vehicle and will stop charging.

My theft system is keeping my car from starting in my 1994 Cadillac Deville
ANSWER : Hello. If the theft light is coming on then it is causing the vehicle not to start. Most of the time the issue is caused by either the key failing or the key sensor located in the key lock cylinder. There is a small chip in the key that provides resistance value to the computer to tell it that the correct key is being used. If there was a spare key I would see if that works. If it does not then it is the sensor in the key lock cylinder. Most of the time the wires from the key lock cylinder break and cause this. It can also be caused by the theft module but that is not as common. If you need to have this problem repaired, consider YourMechanic, as a certified mechanic can come to you to [diagnose why the vehicle will not start] https://www.yourmechanic.com/services/car-is-not-starting-inspection

Oil leaking from under car and "remote control car" sound when car is first started for a few minutes until it warm up.
ANSWER : Hello,
There are a number of things that could make an engine noisy when starting up. Depending on the specific type of sound you are referring to, this will determine how to properly diagnose. If there is a bit of a hissing sound, this may be a sign of a vacuum leak. If this is more of a shrieking sound, this may be a sign of a worn out or out of adjustment serpentine belt. If there is a bit of a howling or growling sound, this may be a sign of a worn out or low on fluid power steering pump. A rattling or pinging sound may be caused by an ignition problem. An engine can ping (or knock) due to an improper combustion process. A "spark knock" is the result of combustion occurring too early. Early combustion can occur from carbon buildup inside the combustion chamber, a lean air/fuel mixture, and advanced ignition timing (spark plug firing too soon). A clattering type sound may be a result of improper lubrication in the valve train which could be a more serious problem and should be addressed as soon as possible. I would suggest having an expert from YourMechanic come to your location to diagnose and inspect your vehicle to ensure everything is in proper working order.

In a keyless entry car, can you also have an alarm say auto watch alarm system installed?
ANSWER : Hello. From what you describe it would appear that the aftermarket alarm system may be having an issue. If the alarm has done this since it was installed then it may be possible that it is wired improperly, or that there is an issue with the alarm system control module. It may be possible that the two alarm systems are interfering with each other somehow, perhaps due to an issue with the transponders or remotes. I would recommend referring to the alarm system manufacturer, or the shop or technician that installed the alarm for more specific support or instructions.

Should I buy this car for $1700
ANSWER : Prior to buying any car, drive the car around and listen for any noises. Then do an inspection on the vehicle to make sure that it is safe to drive. All cars will need maintenance, but if the car was kept up, then the maintenance should be to a minimum.

My car will not start Intermittently. I purchased a new battery 2 weeks ago and yesterday the car wouldn’t start. Got a jump and
ANSWER : The issue you are having is probably due to an intermittent fault in the starter motor itself or a deficiency in the starter electrical circuit, for example a large voltage drop due to a poor ground or a high resistance connection. These issues can be readily diagnosed and resolved on a mobile basis if you request a hard starting diagnostic. If you request that diagnostic, the responding certified mechanic will get this resolved for you promptly. Based on Toyota’s Factory Service Manual, the battery should not be disconnected if the vehicle engine is running. The battery acts as a large resistive voltage sink and consequently taking the battery out of the circuit, while the alternator is still running, can create a voltage spike on the car’s electrical system which is not good for voltage sensitive components such as the engine computer. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

Power steering loss, no belts are turning but the car is running fine. I also have a soft pedal. Whats wrong with my car?
ANSWER : I have only seen this situation once in my 30+ years and it turned out to be a broken crankshaft pulley. Belts are driven by the engine. The crankshaft pulley spins the belts, which in turn spin the air conditioner compressor, power steering and water pumps, and the alternator. The vehicle should be towed to your local repair shop and not driven. Without the water pump spinning to circulate the coolant, the engine will quickly overheat and result in more extensive damage.