OBD2 port pinout: what each pin does
The OBD2 port is a 16 pin connector defined by SAE J1962. Only some pins are standardized. They carry power, ground and the data lines for the five OBD2 protocols, and the rest are left to the carmaker.
Key facts
| Key fact | Detail |
|---|---|
| Connector | 16 pin SAE J1962 connector, in two rows of 8 (pins 1 to 8 and 9 to 16) |
| Power | Pin 16 battery positive, pin 4 chassis ground, pin 5 signal ground |
| CAN (ISO 15765-4) | Pin 6 CAN high, pin 14 CAN low |
| ISO 9141-2 and ISO 14230-4 | Pin 7 K-line, pin 15 L-line (not used on every car) |
| SAE J1850 | Pin 2 bus positive (PWM and VPW), pin 10 bus negative (PWM only) |
| Carmaker's choice | Pins 1, 3, 8, 9, 11, 12 and 13 |
Pin numbers are the same on every OBD2 car, but which data pins are actually fitted depends on the protocol your car uses.
OBD2 pinout table
| Pin | Use | Protocol |
|---|---|---|
| 1 | Manufacturer discretion | Not standardized |
| 2 | Bus positive | SAE J1850 PWM and VPW |
| 3 | Manufacturer discretion | Not standardized |
| 4 | Chassis ground | All |
| 5 | Signal ground | All |
| 6 | CAN high | ISO 15765-4 (CAN) |
| 7 | K-line | ISO 9141-2 and ISO 14230-4 |
| 8 | Manufacturer discretion | Not standardized |
| 9 | Manufacturer discretion | Not standardized |
| 10 | Bus negative | SAE J1850 PWM |
| 11 | Manufacturer discretion | Not standardized |
| 12 | Manufacturer discretion | Not standardized |
| 13 | Manufacturer discretion | Not standardized |
| 14 | CAN low | ISO 15765-4 (CAN) |
| 15 | L-line (optional) | ISO 9141-2 and ISO 14230-4 |
| 16 | Battery positive | All |
SAE J1962 sorts the terminals into standard ones and manufacturer discretionary ones. Carmakers may use the discretionary pins for their own diagnostic lines, so don't assume an unlisted pin is empty.
Which pins your car uses depends on the protocol
OBD2 allows five communication protocols: SAE J1850 PWM, SAE J1850 VPW, ISO 9141-2, ISO 14230-4 (KWP2000) and ISO 15765-4 (CAN). From the 2008 model year, cars sold in the US must use CAN. Earlier cars may use any of the five, and which one depends on the model and year.
- CAN cars use pins 6 and 14.
- ISO 9141-2 and KWP2000 (ISO 14230-4) cars use pin 7, and some also use pin 15.
- SAE J1850 VPW cars use pin 2, and J1850 PWM cars use pins 2 and 10.
- Every car provides battery power on pin 16 and ground on pins 4 and 5.
An ELM327 class adapter takes its power from pin 16 and ground and detects the protocol automatically, so you don't need to know your car's protocol in advance.
Where the connector is
The OBD2 connector (officially the Data Link Connector, or DLC) is generally under the dashboard on the driver's side, near the steering column. EPA guidance treats the area under the driver's side of the instrument panel as the preferred location and allows a few other locations, so on some models it sits behind a small cover, a panel or in the center console.
US federal rules require the connector to follow SAE J1962, which is why the same 16 pin shape is used across makes.
Using OBD Master Pro
OBD Master Pro connects to ELM327 and ELM329 class adapters over Bluetooth Classic, Bluetooth LE, Wi-Fi or USB OTG and supports CAN, ISO 9141-2, KWP2000, J1850 and J1939. Plug the adapter in, turn the ignition on and let the app detect the protocol. Results depend on your car, its modules and your adapter.
Try it on your own car
OBD Master Pro turns your Android phone and a generic ELM327 adapter into a code reader: read and clear codes, view freeze frame and live data, and check emissions readiness.
Keep reading
Related guides: Check engine light on: what to do · How to read an OBD2 code · Stored, pending and permanent codes · OBD2 readiness monitors explained · ELM327 adapter not connecting · How to clear the check engine light · What is fuel trim · OBD2 live data and PIDs · What is a U code? · OBD2 glossary
Common codes: P0171 System Too Lean · P0420 Catalyst Efficiency · P0300 Random Misfire · P0455 EVAP Large Leak
All OBD2 guides · OBD2 by car brand · OBD2 trouble code guides
Sources
- Elm Electronics: ELM327 datasheet (OBD connector pins, protocols and J1939 support)
- Wikipedia: On-board diagnostics (OBD-II diagnostic connector and its pinout)
- SAE J1962: Diagnostic Connector (standard abstract)
- U.S. Code of Federal Regulations, 40 CFR 86.1806-05, On-board diagnostics (govinfo.gov)
- U.S. EPA: OBD Diagnostic Link Connector (DLC) location charts, 1996 to 2000 model years (copy hosted by NC DEQ)
- Elm Electronics (maker of the ELM327 chip): OBD interpreter ICs and protocol support
- OBD Master Pro on Google Play (app features, supported connections and protocols)
Published . Updated . General information only. Details generally vary by model, year and market, so always follow the owner's manual and service information for your vehicle.