Check Engine Light On But No Codes
Check engine light on but no codes? Learn why scanner mode, pending codes, readiness, permanent codes, or scanner limits may be the issue.
Category Symptoms & Problems
Symptom-first diagnostic pages for check engine lights, emissions failures, misfires, and related problems.
Car Shaking and Check Engine Light: What It Means
Car shaking with check engine light on? Learn why misfire is likely, when to stop driving, what scanner data to save, and what to check first.
Check Engine Light Flashing: What to Do First
Check engine light flashing? Learn why active misfire is urgent, when to stop driving, what scanner data to save, and what to check first.
OBD2 Port Not Working: Fuse and Power Checks
OBD2 port not working? Check ignition position, fuse, pin 16 power, ground pins, connector damage, scanner setup, and communication problems.
Check Engine Light Scanner: What to Use First
Choose the right check engine light scanner, read codes, save freeze frame, check live data, avoid clearing too early, and diagnose common codes.
OBD2 Scanner Not Connecting: How to Fix It
Troubleshoot an OBD2 scanner that will not connect, power on, pair by Bluetooth, or communicate with vehicle modules.