OBD2 & Modern Vehicle Diagnostics

The latest vehicles use a more comprehensive diagnostic system. And further the system being used is also being standardised across manufacturers when it comes to engine components and emissions.

OBD2 is the latest set standard. By law in the US (from 1996) and across Europe (EU countries 2001+) cars must be manufactured with a standard diagnostic information set and a standard diagnostic socket.

Although enforced by law, many manufacturers began to incorporate OBD2 into vehicles before it was enforced. The standard in Europe is actually called EOBD but as it is compatible with the North American standard most people refer to it as OBD2.

The standard diagnostic socket is a 16 pin D-shape. The technical term for it is a J1962.

Now while OBD2 is a set standard, amongst different manufacturers the method of communication between the diagnostic equipment and the vehicle can vary. The following protocols exist:

J1850 PWM,

J1850 VPW,

ISO9141-2,

ISO14230-4 (also known as Keyword Protocol 2000 (KWP2000)),

ISO15765-4/SAE J2480 (also known as CAN and becoming the set standard amongst more manufacturers).

So when buying diagnostic equipment ensure that it covers the communication protocol for your particular vehicle or is multi-protocol capable.

To see a diagnostic set up on a Peugeot 306 HDi, click here.

Regards OBD2 standards on Peugeot and Citroen, from experience, OBD2 is on 2001+ petrol and 2004+ diesel models. There are some exceptions where 2000 petrol models will work with OBD2 equipment. Also the 2.0 HDi models may also communicate on some 99+ models.