Which OBD protocol is my car?
Most modern cars use CAN (ISO 15765-4) for OBD-II, while older vehicles may rely on J1850 PWM, J1850 VPW, ISO 9141-2, or ISO 14230. To know exactly which protocol your car uses, connect an OBD-II scanner that reports the protocol, check the owner's manual or VIN, or inspect the ECU labeling. This guide walks you through identifying your car's protocol and why it matters for scanning and diagnostics.
Major OBD-II protocols you may encounter
Here's a quick map of the major OBD-II protocols you might encounter across model years and regions:
- CAN (ISO 15765-4) — the most common on modern cars, typically post-2008 in many markets.
- J1850 VPW — used by some vehicles from certain manufacturers (notably early GM models).
- J1850 PWM — found on some Ford vehicles from earlier eras.
- ISO 9141-2 — older European/Asian cars; slower, uses K-Line for communication.
- ISO 14230 (KWP2000) — older to mid-era vehicles; can be used with slow or fast init sequences.
Knowing the right protocol helps you pick a compatible scanner and ensures your diagnostic tool can communicate with the vehicle's ECU. If you're shopping for a device, prioritize those that can auto-detect CAN, J1850 VPW, PWM, ISO 9141-2, and ISO 14230.
How to identify your car's protocol in practice
Practical steps to identify the protocol:
- Use a modern OBD-II scanner or smartphone adapter. When you connect, the software often reports the protocol (for example, “CAN 500 kbps,” “J1850 VPW,” or “ISO 9141-2”).
- Check the vehicle’s year, region, and manufacturer. In general, vehicles from 2008 onward are overwhelmingly CAN; many 2004–2007 models also adopted CAN, with some lingering legacy protocols in use.
- Consult the owner’s manual or the service/repair documentation for your exact model. Some manufacturers list the supported OBD protocols for each engine/computer family.
These methods should allow you to identify your car's OBD protocol. If you're buying a scanner, ensure it supports all major OBD-II protocols and CAN. If your car is older, confirm compatibility before purchase.
Era-based quick reference: what to expect by year
While there is overlap by region and model, this quick guide helps set expectations about what you’re likely to encounter:
- 1996–2003: OBD-II is standard in the US, with a mix of protocols including ISO 9141-2, ISO 14230 (KWP2000), J1850 VPW, and J1850 PWM depending on the manufacturer.
- 2004–2007: CAN begins to dominate in new models, though some vehicles still support legacy protocols on one or more networks.
- 2008–present: CAN (ISO 15765-4) is the default for almost all new cars in major markets; a few niche models may still use older protocols on secondary networks.
Remember, the exact protocol can vary by model and engine control module family, so always verify with a live scan or official documentation for your vehicle.
Summary
To determine which OBD protocol your car uses, start with a capable OBD-II scanner that reports the protocol during connection. If you already know your car’s year and region, you can narrow down expectations: CAN is the standard for most modern vehicles, while older models may use J1850 PWM/VPW, ISO 9141-2, or ISO 14230. When in doubt, consult the owner’s manual or use VIN-specific documentation to confirm the exact protocol and ensure your diagnostic tools are fully compatible.
