All about OBD2
What’s worth knowing to diagnose a car through the OBD socket, without the jargon. It applies to Final OBD and, almost all of it, to any other app.
First things first
The adapter changes everything
Nearly every complaint that an app can’t read a car is really about the adapter. Before anything else, this:
- ELM327 clones that say v1.5 or v2.1 are copies: they drop messages, can’t handle several readings at once, struggle on the K-line and freeze.
- A good one, like the vLinker MS and MC+ we recommend, drops nothing and answers quickly.
- On iPhone it has to be BLE, wifi or Apple certified; classic Bluetooth won’t work.
- Final OBD measures yours when it connects and tells you its level: Very fast, Fast, Slow or Very slow.
Mechanics guide
How your car works, system by system: EGR and particulate filter, AdBlue, ignition and catalyst, batteries... With the faults we see most and what you can check yourself.
Fault codes
What each generic OBD2 code means, with its causes, its symptoms and whether you can keep driving.
The guides
OBD2 adapters: clones, good ones and which to buy
ELM327 clones, classic Bluetooth, BLE or wifi, iPhone and the readers we recommend.
How to read and clear your car’s fault codes
Step by step, what each code means and when it makes sense to clear.
The check engine light: steady, flashing and what to do
Steady or flashing, whether you can keep going and why it sometimes goes off by itself.
OBD readiness monitors before inspection
What OBD2 emissions readiness monitors are, how to check them with Final OBD before an inspection and why an app report is not a pass.
The OBD2 readiness monitors
What each monitor checks, why they show not ready and how they complete.
What OBD2 is and since when your car has it
What it’s for, the difference between OBD2 and EOBD, and the year it became mandatory.
The OBD2 connector: where it is and what each pin carries
Where to look for it and what each of its 16 pins is for.
The OBD2 protocols: how your car talks
CAN, K-line (ISO 9141-2 and KWP2000) and J1850: which car uses which.
The OBD2 modes, one by one
Live data, fault codes, clearing, pending, VIN and permanent: what each mode asks for.
OBD2 live data and its normal values
Rpm, temperatures, fuel trims, oxygen sensors, load and boost: what each PID is and which value is normal.