Introduction on the On-board Diagnostic (OBD) modes of operation (also called diagnostic services). If your vehicle is a or newer model, it comes equipped with an On-Board Diagnostics System (OBD II). This system is designed to catch emissions. On-board diagnostics (OBD) is a special system which is implemented in nearly all engine components. It is actually an electronic system which helps in keeping.


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OBD Scantool The handheld one is the one usually identified as a scantool.

On-Board Diagnostics (OBD) – introduction to the Modes of Operation (Diagnostic Services)

It can be used regardless of the on board diagnostics of the vehicle, as long as both are OBD 2 compliant. The progress in electronics makes it possible to diagnose all or most of the sensors and actuators connected to an engine control unit.

A current Engine Management System EMS for a 4 cylinder gasoline engine includes more than 25 sensors and about 30 to 35 actuators. on board diagnostics

All these components have to be diagnosed electrically, some of them also against rationality failures. In addition, drive-by-wire systems as electronic throttle control require enhanced diagnostic functionality for safety reasons to avoid i.

OBD-I systems, which on board diagnostics different scan tools for different vehicle models, began to be included on vehicles in the late s.

Analysis of vehicle black box data may be performed on a periodic basis, automatically transmitted wirelessly to a third party or retrieved for forensic analysis after an event such as an accident, traffic infringement or mechanical fault. Since OBD-II stores trouble codes for emissions equipment, the on board diagnostics computer can query the vehicle's on board diagnostics computer and verify there are no emission related trouble codes and that the vehicle is in compliance with emission standards for the model year it was manufactured.

Introduction to On Board Diagnostic (OBD)

This is opposed to scanners used primarily for active fault diagnosis, tuning, or hidden data logging. Auto enthusiasts have traditionally installed additional gauges such as manifold vacuum, battery current etc. The OBD standard interface has enabled a new generation of enthusiast instrumentation accessing the full range of vehicle data used for diagnostics, and derived data such as instantaneous fuel economy.

Instrumentation may take the form of dedicated trip computerscarputer or interfaces to PDAs[30] smartphones, or a On board diagnostics navigation unit.

Additionally, erasing the codes may hide problems and make it more difficult to diagnose and fix your vehicle.

DON'T take the vehicle in for a test if you have a device that monitors your driving habits plugged in to the connector below the dashboard. You must remove the device and replace it after the test.

Emission stations are required to fail the vehicle on board diagnostics such a device is plugged in.


The On Board Diagnostics system on board diagnostics composed of a computer that monitors the emissions system and key engine components. It can usually detect a malfunction or deterioration in these components before the driver becomes aware of the problem.

EPA has required auto makers to install OBD systems on all cars and light-duty trucks made since on board diagnostics OBD systems are designed to alert the driver when a component in the engine management or emissions systems begins to deteriorate or malfunction.

On-board diagnostics - Wikipedia

Early detection of minor problems, followed by timely repair, can often prevent more costly damage to components such as the catalytic converter.

How does OBD work? This on board diagnostics cannot be turned off until the necessary repairs are completed or the condition no longer exists.


When you take your car in for diagnosis or for an annual emission inspection, the repair technician retrieves the trouble codes from the computer using a "Scan On board diagnostics.

Under certain conditions, the dashboard light will blink or flash. This indicates a severe problem. On board-diagnostics OBD is the inclusion of circuitry within a device that can indicate proper function and calibration of the main unit or specific fault states.


ODB has been used in cars since the s.