MotorBitHome / Guides
OBD2 guides
Setup first, then the numbers, then the light. Each page ends with what to confirm on the car.
iPhone & adapter
SETUP
How to connect OBD2 to iPhone
FIX
ELM327 not connecting to iPhone
GEAR
Fake vs real ELM327 adapters
GEAR
What is ELM327?
SCAN
How to read OBD2 codes with an iPhone
The light
LIGHT
Why is my check engine light on?
CLEAR
How to clear a check engine light (the right way)
SMOG
Readiness monitors & emissions tests
FEEL
Symptom guides — rough idle, shake, MPG, failed smog
Live data
PIDS
Live data glossary — MAF, O2, coolant, throttle, load
DATA
Freeze frame explained
FUEL
Fuel trim (STFT / LTFT) explained