Read the Climate Control Self-Diagnostic Codes

The Honda Jazz (Mk3/GK, 2015–2020) — sold as the Fit in some markets — hides a self-test inside its climate-control unit. The right button sequence makes the panel run a full HVAC diagnostic, light all its segments, then blink any stored heating/air-conditioning fault codes, with no scan tool needed. Honda never printed it in the handbook. This guide shows how to use it on the Mk3 Jazz.

What the Self-Diagnostic Mode Does

The Jazz’s climate module monitors its own air-mix (temperature blend) motor, mode motor, blower, recirculation flap and temperature sensors. When you enter the self-test, it cycles those actuators, checks each sensor responds and reports any Diagnostic Trouble Codes (DTCs) by blinking an indicator. It is read-only — it reports faults without altering settings or risking any damage. The Mk3 Jazz came with both a manual dial A/C and, on EX trim, a single-zone automatic climate control; each has its own way in.

How to Enter Self-Diagnostic Mode

1. Park, doors closed. Turn the ignition to LOCK (0), then back to ON (II) — engine off (push-button cars: press START once without the brake).
2. On automatic climate control: press and hold the climate ON/OFF button, then press the rear-window defogger five times within 10 seconds, and release.
3. On manual dial A/C: press and hold the recirculation and rear-window defogger buttons while turning the ignition to ON; the recirculation indicator lights for about 2 seconds, then the test begins.
4. The unit lights all segments, runs its actuators, then begins blinking the result.

How to Read the Codes

• No fault stored: the indicator/segments do not illuminate or blink.
• A fault present: the display alternates “88” (all segments lit) with the fault segment (A–N) or a numbered code every second.
• Special case: if segments A, C, E, G, I and L all light together, suspect an open in the common ground wire.
• Multiple faults are shown in sequence — note each one.

How to Exit and Clear the Codes

To exit, turn the ignition to LOCK (0). To clear stored codes, fix the fault and re-run the sequence, or disconnect the 12 V battery for a few minutes. Clearing only erases the memory — a live fault re-logs on the next test, so always diagnose the cause first.

Safety Note

This is Honda’s factory diagnostic, run parked with the engine off. The blower and internal flaps move during the test — that is normal. It is isolated from the engine, airbag and brake systems, so you cannot damage anything by running it. Keep the Jazz stationary throughout.

Frequently Asked Questions

How do I know if my Jazz has automatic or manual climate?

Automatic climate (EX trim) has an AUTO button and a digital temperature readout; manual A/C uses rotary dials. Use the matching entry sequence above — both reach the same self-test.

What do the A–N segments mean?

Each lettered segment maps to a specific circuit or sensor in the climate unit. The alternating “88” is the lamp test; the lettered segment shown alongside is the actual fault to chase.

Nothing lit up — is my air conditioning fine?

No illumination means no electrical HVAC fault is stored, which is reassuring. But low refrigerant or a worn compressor often logs nothing, so a clean test does not always mean cold air.

Does the hybrid Jazz use the same procedure?

Yes — the climate-control electronics are shared, so the entry sequence is identical on petrol and hybrid Mk3 Jazz models.

Will the test reset my settings?

The panel may revert to default on exit, but nothing permanent is lost. Just set your temperature and fan speed again afterwards.

Because these flashing segments and numbers are diagnostic trouble codes, you can look up what a specific HVAC or related fault means on autodtcs.com.