Gazza82's 1998 Alfa Romeo 156 TSpark 2.0

156 Diagnostics

Relates mainly to the diagnostics software and hardware around to work with the early pre-2001 156.

Which type?

The EOBD (European On Board Diagnostics) regulations are the European equivalent of OBD-II, and apply to all passenger cars of category M1 (with no more than 8 passenger seats and a Gross Vehicle Weight rating of 2500 kg or less) first registered within EU member states since January 1, 2001 for petrol (gasoline) engined cars and since January 1, 2004 for diesel engined cars.

For newly introduced models, the regulation dates applied a year earlier - January 1, 2000 for petrol and January 1, 2003 for diesel.

For passenger cars with a Gross Vehicle Weight rating of greater than 2500 kg and for light commercial vehicles, the regulation dates applied from January 1, 2002 for petrol models, and January 1, 2007 for diesel models.

The technical implementation of EOBD is essentially the same as OBD-II, with the same SAE J1962 diagnostic link connector and signal protocols being used.

Pre Jan 2001 petrol, pre-Jan 2004 were Fiat's version of OBD, later models were EOBD compatible. There are no OBD2/OBD-II Alfas at all since that is a standard for cars sold in the USA from 1996. Alfa hasn't sold anything in the USA since 1995 so they have never used it. Also Diesels are not subject to the same standard in the EU so it is often hit and miss for these prior to Sept-2004.


Petrol cars and late diesels use the EODB protocol and there are a larger number of products available to work on these models, although AlfaDiag has recently been upgraded to work on some of the newer ECU models, it may not have all the "bells and whistles" yet. Click here to see some pictures from AlfaDiag in use.

OBD Interfaces

You will need and OBD interface cable to connect your laptop to the cars diagnostic port. This is housed behind the fuse box cover in dashboard to the right of the steering column (RHD cars).

USB VAGCOM Interfaces

These are now the more common interface to use as most newer laptops don't have a serial port.

Serial Port Interfaces

I bought my serial port OPTO interface from Andy Whittaker for use with the AlfaDiag software. Telmo's interface one from a german company called GSEL Electronics, and Click here to see the pictures of the two interfaces.

OBD Codes

Most of the standard OBD codes are the same on the Alfa, although as will all manufacturers there are more specific codes that aren't so easy to translate so here a Google search comes in handy Click here to see a list of the ODB-II fault codes.

Page added: 11 August 2005, last updated 8th Oct 2013