what is the diference betwen a obd1 and obd2?

9 Answers

  • 1 decade ago
    Favorite Answer

    OK, this is my short and not so technical answer. (You should see the long version.....)

    OBD1 had sensors to run the engine and it could turn on some emission controls like an EGR valve. It wasn't smart enough to know, however, if the EGR was even working or if the Catyliyic Convertor was working for example. That's why OBD1 car's need smog checks on a rolling dyno with a sniffer in the tailpipe.

    OBD2 is the same OBD1 system with a slew of secondary sensors that have nothing to do with how the car runs but rather check to make sure the pollution control devices are actually working.

    An OBD2 system will now have a temperature sensor in the EGR tract and/or a position sensor on the actual valve too see if the temperature jumps rapidly and/or the valve moves when the EGR is turned on to ensure that the valve is actually opening and flowing.

    An OBD2 system will also have the same OBD1 02sensor up before the Catylitic Convertor but now has a second 02 sensor AFTER the Catylitic Convertor. It's so simple it's ingenious. The Computer looks at the waveform of the OBD1 02 sensor before the Cat. and compares it to the OBD2 02 sensor after the Cat. Since the Cat. burns off more of the spent fuel etc. then the OBD2 02 sensor better be reading a different 02 content if the cat. is working. If they both read the same all the time then Cat. is obviously doing nothing. All the while, the front OBD1 sensor is still giving the air/fuel inputs that tells the computor how to run the engine while the rear OBD2 sensor is just the checksum sensor with no influence on how the engine runs at all.

    This is how they can smog check an OBD2 car just by plugging in and checking for any trouble codes. There a very smart reliable system.

    Source(s): Hope this made sense and answered your question.
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  • 4 years ago


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  • Anonymous
    1 decade ago

    OBD II is a newer generation of on board diagnostics. The trouble codes were standardized for all makes and models. OBD 2 had to be installed in all cars by 1996, some manufacturers like toyota and mazda have OBD 2 since 1994.

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  • Eric F
    Lv 6
    1 decade ago

    OBD I is in all computerized cars up to 1995. It is proprietary for each manufacturer.

    OBD II is standardized, and EVERY car manufactured for the USA from 1996 to current MUST have an OBD II compliant car computer. all codes are generic, the manufacturer picks the codes it wants to use. There are also codes for manufacturers, which can also be read using a single scan tool.

    OBD 1 you need to have multiple scan tools.

    OBD II scan ports are ALWAYS locatd under the driver's side . on honda's they are behind the ashtray.

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  • Anonymous
    7 years ago

    When you’re buying a vehicle, two terms that will often confuse you are OBD1 and OBD2. Naturally, these will be taken in the automotive context.

    The acronym refers to On-Board Diagnostics. Basically, it defines a vehicle’s capability to diagnose, or report itself. For example, if you have a high-tech OBD system in your

    car, and it has a problem, the OBD system will be the one to self-diagnose, or ‘tell’ the repair technician what is wrong with the engine.

    With advancements in technology, came the improvements of OBD systems, and the latest ones use a standardized digital communications port that provides real-time data. This

    results in faster diagnostics of a vehicle’s problem, and more efficient remedies can be provided for the problem.

    Now, here’s the difference between OBD1 and OBD2. With OBD1, the goal was to develop a diagnostics system which focuses on the emission control systems of a vehicle. When it

    came to its effectiveness, the OBD1 was not really that successful in forcing drivers to pass the emission control system’s test.

    OBD2, on the other hand, is a definite improvement to the OBD1. OBD2 has better signalling protocols and messaging formats. When used in emission control system tests, it can

    provide better results for a vehicle’s parameters.

    Meanwhile, when considering their manufacturing dates, OBD1s were introduced long before the OBD2 models, which only started in the early 1990′s. The OBD2 is a better system,

    in the sense that it provides standardized trouble codes for car owners who experience engine problems.

    Finally, OBD1 is typically connected to the console, so that the port can be diagnosed and data can be read. OBD2 is remotely used to diagnose ports, and reads data through a

    Bluetooth connection. As such, it is easier to diagnose a problem remotely if you have a car made with an OBD2 system.


    1. OBD1 is connected to the console of a car, while OBD2 is remotely connected to the vehicle.

    2. OBD1 was used during the earlier years of the car manufacturing industry, while OBD2 was only introduced in car models produced in the early 1990′s.

    3. OBD1 has good diagnostic capabilities, while OBD2 has better signalling protocols and messaging formats.

    Obd2works.com - Online Shopping for OBD2,OBD2 Scanner,Car Diagnostic Tool

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  • 1 decade ago

    They determine what type of computer control you have in your car. OBDI is early 90's and later OBDII is the second generation computer used for most of the 90's and so on.....

    OBD means On Board Diagnostics, which is what the mechanic checks when they "plug in the computer"(check what you on board computer tells them about how the cars running helping in the diagnostic of a problem).

    Source(s): I was a mechanic after highschool for a few years
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  • Anonymous
    4 years ago

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  • 4 years ago

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  • 4 years ago

    What Is Obd2

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