All About EOBD
Monday, 05 October 2009 12:11

The History, Details and Information on EOBD

EOBD is a standard used on cars to report diagnostic information about the vehicle's electronics and emission control system.

It stands for European On Board Diagnostics and applies to European cars manufactured since 2001 for petrol vehicles and 2003 for diesel vehicle ones. EOBD is a version of OBD-II ( a USA standard for cars sold after 1996)

EOBD defines how a diagnostic scan tool is connected and used with a vehicle, meaning a single diagnostic tool that is EOBD capable can diagnose any vehicle manufactured after 2001/2003.

The EOBD standard and also previous USA versions, determine the following:

  • The location of the vehicle's diagnostics connector
  • Its physical shape and size
  • What pins are used in the connector
  • What signals & messages the tester can use talk to the vehicle
  • What information must be available from the vehicle


Since the 1980's vehicles have had the capability to provide diagnostic information via either blink codes, displayed on the vehicles dash board or via a diagnostic link to a scan tool.

General Motors implemented the ALDL protocol (Assembly Line Diagnostic Link), this was used during the vehicle assembly and monitored only a few systems, this was not intended for use outside of the factory and only blink codes were meant to be available to the mechanic.

Around 1987 the California Air Resources Board required all new vehicles sold in California from 1988 to have a basic OBD capability (OBD-I).
The California Air Resources Board issued the OBD-II standard around 1994 for all vehicles sold in California from 1996. Error codes and the connector to use was also standardised in this version of ODB.

In 1996 the OBD-II standard was made mandatory for all cars sold in the United States.

2001 saw the European Union make the EOBD standard mandatory in the Directive 98/69/EC.

These standards are aimed at monitoring emissions systems within the vehicle and providing diagnostics information or warning signals to the driver. The EOBD standard is the most complex of all of the OBD variants.

The Standard

The EOBD standard defines the following information about the system on the vehicle.


It uses a standard J1962 connector and must be located in the passenger compartment, usually found around the driver's foot well.

The EOBD pins on the J1962 connector are defined in the J1962 standard:

1 - Ignition Positive
2 - J1962 + Data
4 - Chassis Ground
5 - Signal Ground
6 - CAN High Data
7 - ISO K Line Data
10 - J1962 - Data
14 - CAN Low Data
16 - Battery Positive


The communications between the tester and the vehicle can use various different protocols:

  • J1850 PWM
  • J1850 VPW
  • ISO 9141
  • KWP2000
  • CAN

The vehicle only needs to support one of these protocols for it to comply with EOBD.

J1850 PWM is mainly found on Ford vehicles in Europe, J1850 VPW is mostly Chrysler vehicles in the US.
The CAN protocol is being adopted by manufacturers as the default diagnostics protocol to use in new vehicles.
KWP2000 (key word 2000) and ISO are very similar protocols that use pin 7 on the J1962 connector.

Data Available

The vehicle can provide various amounts of data, from simple trouble code numbers to pending trouble codes (continuous monitoring), freeze frame information, real time component data (PIDs), actuator control, oxygen sensor tests and non-continuous tests.

The only data that the vehicle must supply is trouble codes and it is not required to supply any other information. There are 2 types of trouble code, generic codes that are not specific to a manufacturer and enhanced codes that are specific to a manufacturer or vehicle. Enhanced codes require extra information about the manufacturer to look up the correct error code meaning and description.

For more information on EOBD trouble codes please see this article: All about EOBD trouble codes


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