Plug in any OBD-II adapter, launch the app, and get plain-English explanations of every check engine code — plus severity ratings and repair guidance, in under 60 seconds.
Every check engine code — including manufacturer-specific ones — decoded in under a second. Covers engine, transmission, brakes, airbag, and more. No cryptic codes, no guessing.
Every code ranked Safe / Monitor / Urgent / Critical. Know immediately whether you're looking at a loose gas cap or a towed-home situation.
Real-time fuel trims, O2 sensor readings, coolant temp, RPM, MAF flow. See what the sensor actually saw at the moment the code triggered.
Based on your vehicle's mileage and code history, NexusCode surfaces which issues are likely to escalate. Fix the urgent ones first.
Instant parts lookup — OEM, aftermarket, 3D-printable. Live pricing, local availability, and links to order. One tap from diagnosis to checkout.
Hybrid and plug-in vehicle support: battery charge level, thermal readings, and core high-voltage system codes — coverage most scan tools skip.
You need one thing: a Bluetooth or WiFi OBD-II adapter. That's it. NexusCode does the rest.
Connect any Bluetooth or WiFi OBD-II adapter to your car's diagnostic port (under the steering wheel). Takes 10 seconds.
Launch the app and connect to the adapter. NexusCode reads every fault code across all major systems — engine, transmission, brakes, airbag, and more.
Each code is explained: what triggered it, how serious it is (Safe / Monitor / Urgent / Critical), whether you can fix it yourself, and estimated repair cost.
Don't have an adapter? See which one to buy →
Cylinder 1 isn't firing consistently. Most common cause at this mileage: worn spark plug. Could also be a bad ignition coil or fuel injector.
The catalytic converter isn't cleaning exhaust as efficiently as expected. 9 times out of 10 at this mileage, it's the downstream O2 sensor — not the cat.
A small device that plugs into your car's diagnostic port (under the steering wheel column). It translates your car's fault codes into data your phone can read. Any Bluetooth or WiFi OBD-II adapter works with NexusCode.
Yes. NexusCode talks to your car through the OBD-II port, so you need a Bluetooth or WiFi adapter. See our recommended adapters →
Any adapter that supports Bluetooth Classic or BLE, or WiFi. Popular options include OBDLink CX, Vgate iCar Pro, and OBDLink MX+. We have a full compatibility guide with setup instructions.
Yes — the core scan and code explanations are free. We also offer a Pro tier for advanced sensor data, freeze frame capture, and history tracking.
No. Reading codes does not modify anything on your car. The OBD-II port exists for exactly this purpose — it's the same port mechanics and dealerships use.
Any US-sold car from 1996 onward is required to support OBD-II — that's over 99% of vehicles on the road today. Electric and hybrid vehicles are supported for the systems that apply (battery, charging, motor).
"The check engine light has been telling you something for years. You just didn't speak its language."
NexusCode is built for the 200 million vehicles on US roads over 12 years old — the ones dealers make the most money off because you don't know what's actually wrong. We fix that.
Plug in any OBD-II adapter and NexusCode tells you exactly what's wrong with your car, in plain language — no mechanic required.