These instructions apply to the Mazda 3 Mk3 (BM/BN) 2013-2018.
For other models, please choose your vehicle here.
The Mazda 3 (Mk3/BM–BN, 2013–2018) has a hidden instrument-cluster Test Mode you can open from the driver’s seat with no scan tool. Holding the dash trip-reset button while you switch the ignition to ON drops the cluster into a numbered self-test that sweeps the gauges, checks every warning lamp and LCD segment, sounds the chimes and shows live sensor readings — a quick free check before booking diagnostics.
What Test Mode is and what it shows
This routine makes the BM/BN cluster run a fixed sequence of self-checks, each identified by a code number in the odometer window. As you step through it you can verify:
- The warning and indicator LEDs, lit one group at a time
- The LCD segments and backlight, to catch dead pixels
- Full needle sweeps of the speedometer (rests near 60) and tachometer (rests near 3000 rpm)
- Fuel-gauge and coolant-temperature gauge sweeps
- Live fuel-sender values and the dash and turn-signal chimes
It is the cluster testing itself and the signals reaching it, so a gauge that will not sweep is a cluster issue, while one that sweeps fine but misreads on the road points to the sender or wiring.
How to enter the hidden diagnostic menu
- Turn the ignition fully OFF.
- Press and hold the trip-reset button on the cluster.
- While holding it, switch the ignition to ON (position II), or on keyless cars press START twice without pressing the brake. Do not start the engine.
- Hold the trip button until TEST shows in the odometer display, then release.
- Press the trip button to advance through the numbered tests.
Reading the gauges and codes
Each press steps to the next code. The early codes light the LEDs and run the LCD segment check; a missing segment or dead lamp is a hardware fault in the cluster. The gauge codes drive the speedometer, tachometer, fuel and temperature needles through their full range — watch for sticking or lag. Numeric codes show live fuel-sender and input values, which quickly separates a faulty gauge from a faulty sender. Make a note of anything abnormal before exiting.
How to exit
Switch the ignition OFF, then back ON, to leave Test Mode. Nothing is altered by viewing the tests, and the cluster behaves normally at the next start.
Frequently Asked Questions
My 2014 Mazda 3 has keyless start — how do I reach ON? Hold the trip-reset button and press the START button twice without touching the brake. That sets the ignition to ON, and the cluster will show TEST if you keep holding.
Does this work on the Mazda 3 hatch and sedan? Yes. Both BM and BN body styles share the same cluster and trip-button sequence.
Will it clear my service reminder or check-engine light? No. Test Mode only displays data; it does not reset the service indicator and cannot clear an engine fault. Use the engine ECU scan for that.
Why does it exit immediately? You probably released the trip button too soon or went past ON to START. Reach ON only, keep holding, and wait for TEST.
Can I damage anything by running every test? No, with the engine off the tests only exercise the gauges, lamps and chimes. Never run the mode while the car is moving.
To decode any fault code you record here, visit autodtcs.com.
Independent guide — not affiliated with Mazda. Always follow your official service manual and safety precautions. Read our full disclaimer.