MechaOBDTHE MECHAOBD FIELD GUIDE
Know a little more.
Guess a little less.
Warning lights, trouble codes, and the questions in between. Practical guides to help you understand your car and decide what to check next.
START HERE / THE ESSENTIAL GUIDE
Why Is My Check Engine Light On? What to Check First
Your check engine light can mean anything from a loose gas cap to an active misfire. Learn what to check, when to stop driving, and how to read the code.
Find your next step.
05 GUIDESWarning lights
Flashing vs. Solid Check Engine Light: What Each One Means
A flashing check engine light is more urgent than a solid light. Learn what each signal means, when to stop driving, and what information to scan.
iPhone diagnostics
How to Read Check Engine Light Codes With an iPhone
Use an iPhone, a Bluetooth Low Energy OBD-II adapter, and MechaOBD to read check engine codes and vehicle data safely from your driveway.
P0420Code guide · P0420
P0420 Code: Diagnose Before Replacing the Catalytic Converter
P0420 means catalyst efficiency below threshold on Bank 1—but it does not automatically prove the converter is bad. Learn what to test first.
P0300Code guide · P0300
P0300 Code: What Random/Multiple-Cylinder Misfire Really Means
P0300 means random or multiple-cylinder misfire detected. Learn when to stop driving, what can cause it, and how to diagnose without guessing at parts.
OBDLINK CXSetup guide · iPhone
How to Connect OBDLink CX to an iPhone With MechaOBD
Connect an OBDLink CX to your iPhone safely, run a MechaOBD scan, and fix the most common Bluetooth and vehicle communication problems.
Photography: Nick Fewings and Maxim Hopman / Unsplash. Catalytic converter: Ballista / Wikimedia Commons, CC BY-SA 3.0 (resized and cropped; image adaptations under the same license). Photo credits.
