A small Bluetooth adapter plugs into your car's OBD-II port (under the dashboard on 1996 and newer cars) and sends your check-engine codes to an app on your phone. Knowing your codes before you call a shop helps you ask better questions and compare diagnostic offers.
What to look for
- Works with your phone: many low-cost adapters are Android-only. Check for iPhone support if you need it.
- Subscription or not: some apps lock explanations or features behind a yearly plan. Know the full cost before you buy.
- Shows pending codes and freeze-frame data, not just active codes.
- Unplug it when you're done if the maker says it can drain the battery while parked.
Our picks
BlueDriver Bluetooth Pro
Most drivers who want clear explanations
- Phones:
- iPhone and Android
- Subscription:
- No subscription
Well-reviewed app with plain-English code reports and repair information.
Check current price ↗OBDLink MX+
Enthusiasts who want deeper data
- Phones:
- iPhone and Android
- Subscription:
- Core app included; some advanced features may cost extra
Fast, reliable connection with enhanced diagnostics on some makes. Works with many third-party apps.
Check current price ↗FIXD
Simplest setup
- Phones:
- iPhone and Android
- Subscription:
- Basic code reading free; premium features are a yearly subscription
Very easy to use. Check what's included before subscribing.
Check current price ↗Budget ELM327-style adapters
Reading codes on a tight budget
- Phones:
- Often Android-only; check the listing
- Subscription:
- Depends on the app you use
Low cost and fine for basic codes with apps like Torque Lite. Quality and compatibility vary.
Check current price ↗No adapter? No problem
Many auto parts stores will read your codes for free. Write down every code, including pending ones, and add them to your ShopCheck request so shops can quote an accurate diagnosis.