The OBD2 connector is the interface through which every modern diagnostic tool communicates with the vehicle – but not every connection is the same. Depending on the vehicle class, manufacturer and model year, different connector types and pin assignments are used, and this is exactly where the most common source of error lies in practice: if the connector doesn't fit exactly, no connection is made at all, or only an incomplete one. The right adapter & accessories from our range reliably solves this problem.
OBD1 vs. OBD2: what the difference means for your adapter
OBD2 is the 16-pin diagnostic connector standardised across Europe since the early 2000s (per SAE J1962), while OBD1 is the umbrella term for the manufacturer-specific diagnostic connectors that were common before that, without a uniform standard. On older vehicles with an OBD1 connector – such as early GM, Opel or Fiat models – a standard OBD2 connector doesn't fit directly onto the vehicle's socket. Here a specific adapter cable is needed to translate the manufacturer's own pin assignment to the standardised 16-pin OBD2 connector of your diagnostic tool. Vehicles with extended workshop diagnostic systems (e.g. Mercedes SD Connect or VW/Audi ODIS) are also often accessed via a separate, multi-pin round connector instead of the simple OBD2 connector, in order to reach additional control units and functions.
OBD2 adapters for trucks and commercial vehicles: different standard, different connector
On trucks, buses and heavy commercial vehicles, the 16-pin car OBD2 connector is generally not used; instead, a different, usually 9-pin round connector according to the SAE J1939 standard (deutsch connector) is used. Anyone wanting to use a car diagnostic tool on commercial vehicles too therefore needs a matching adapter cable between the 16-pin OBD2 connector of the diagnostic tool and the 9-pin connector of the commercial vehicle. Without this adapter, no connection can be established, even if the diagnostic tool and software are fundamentally truck-capable.
What to look for when buying an OBD2 connector
Not every adapter cable is equally well suited to every purpose. Before buying, you should check the following points:
- Correct pin count and connector shape: 16-pin OBD2, manufacturer-specific round connectors (e.g. 38-pin, 14-pin) or commercial-vehicle connectors (9-pin) differ in shape and pin assignment – the wrong connector simply won't fit.
- Compatibility with the diagnostic tool used: adapter cables are often designed for a specific interface (e.g. GM Tech 2, VAS 6154, SD Connect C4) and should match it.
- Build quality: gold-plated or tin-plated contacts and a robust, shielded cable sheath prevent contact problems and loose connections in everyday workshop use.
- Complete pin assignment: to access all control units, all required pins actually need to be connected, not just some of them.
You'll find an overview of suitable cables for older and brand-specific connectors in the OBD1 Adapterkabel PKW category.
Which OBD2 connector fits my vehicle?
On most cars from model year 2001 onwards, the standardised 16-pin OBD2 connector fits directly onto the vehicle socket; for commercial vehicles and manufacturers with their own workshop diagnostic system, however, you need a special adapter cable.
Cars: as standard, the 16-pin OBD2 connector is sufficient for current cars. Exceptions are vehicles with brand-specific workshop diagnostics such as Mercedes (SD Connect, 38-pin/14-pin) or VW/Audi/Škoda/Seat (ODIS, VAS 6154 modules), as well as electric vehicles like Tesla, whose diagnostic connector differs from the 16-pin standard and requires its own adapter cable.
Trucks/commercial vehicles: here a 9-pin adapter to SAE J1939 is generally required to switch from the diagnostic tool's 16-pin OBD2 connector to the commercial vehicle interface.
Tesla Model 3 26-Pin to 16-Pin OBD2 Adapter Cable
Tesla vehicles show particularly clearly how much OBD2 connectors can differ by manufacturer: the 26-pin diagnostic connector in the Tesla Model 3 doesn't fit directly onto standard 16-pin diagnostic tools. This adapter cable establishes the connection to the standardised OBD2 connector (€19.99):
OBD2 16-Pin Adapter Connector for GM Tech 2 Diagnostic Tool
With GM vehicles (Opel, Chevrolet, Saab) and the GM Tech 2 diagnostic tool too, a dedicated OBD2 adapter connector is needed to correctly wire the 16-pin connector and reach all control units (€49.00):
The right OBD2 connector determines whether your diagnostic tool can establish a connection to the vehicle at all – for standard cars, the standardised 16-pin connector is enough, but for commercial vehicles, brand-specific workshop systems and electric vehicles, there's no way around the matching adapter cable. If you have questions about choosing the right adapter for your vehicle, our team will be happy to advise you personally on 0711-3654 4645. Buy now, pay later is available via Klarna or PayPal.