Modern fuel-injected scooters and small motorbikes have quite a few lights on the dash: the FI malfunction lamp, ABS, smart key, coolant temperature and idling stop. This guide explains what each light means and what to do, based on Honda owner’s manuals for the Honda Vision sold in Vietnam and the Honda ADV160 with ABS, so that on a road trip you know which lights let you carry on carefully and which mean slow down, stop and get the bike checked.
Quick answer: what to do when a motorcycle warning light comes on
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- The FI light coming on and then going off when you turn the key to On is normal; the Vision manual says to confirm it is off before starting.
- If the FI light comes on while riding, there may be a serious problem with the fuel injection system: reduce speed and have the bike checked as soon as possible.
- The ABS light comes on with the ignition and goes off at about 10 km/h; if it comes on or flashes while riding, the brakes still work but without the anti-lock function.
- The coolant temperature light: pull over safely, switch off and let the engine cool.
- The smart key light flashing 5 times: the key fob battery needs replacing.
- On a rental bike: take a photo of the dash while the light is on and tell the owner before trying to fix anything.
Which lights are normal when you switch on
Several warning lights come on briefly when you turn the key to On as a self-check, then go off. That is not a fault:
- PGM-FI malfunction indicator lamp (MIL): comes on when the key is turned to On (Honda Vision); comes on briefly at key-on (Honda ADV160). Before starting, the Vision manual says to confirm it has gone off.
- ABS light (bikes with ABS): comes on with the ignition and goes off when your speed reaches about 10 km/h.
- Coolant temperature light (liquid-cooled bikes): comes on briefly at key-on.
- Smart key light: comes on when the bike and key have verified each other, and goes off when you turn the switch to On.
The Vision manual also says that if any indicator does not light as it should, the bike should be checked. The ADV160 manual likewise treats an ABS light that does not come on at key-on as abnormal.
Quick reference: motorcycle warning lights
| Light | Abnormal sign | What to do | Source |
|---|---|---|---|
| PGM-FI malfunction lamp (MIL) | Comes on while the engine is running | Reduce speed and have the bike checked as soon as possible | Honda Vision, ADV160 |
| ABS | Comes on or flashes while riding; does not come on at key-on; does not go off above 10 km/h | Reduce speed and get it checked soon; brakes work as a conventional system | Honda ADV160 |
| Coolant temperature | Comes on while riding, acceleration becomes sluggish | Pull over, switch off, let it cool, check for leaks and coolant level | Honda ADV160 |
| Battery charging condition | Comes on while riding | Possible low battery voltage or battery degradation; have it checked | Honda ADV160 |
| Smart key | Flashes 5 times; flashes while the switch is On | Replace the key battery; check you still have the key with you | Honda Vision, ADV160 |
| Idling stop | Flashes when the engine stops itself at a halt | Normal; do not walk away from the bike while it is flashing | Honda Vision |
The FI light (MIL): keep going or stop?
Both the Honda Vision and Honda ADV160 manuals say that if the PGM-FI malfunction lamp comes on while riding, there may be a serious problem with the fuel injection system, and you should reduce speed and have the bike inspected as soon as possible.
- Slow down straight away and avoid overtaking, long climbs or extra load.
- Find a safe place to stop and check whether the bike hesitates, jerks, makes strange noises or smells of burning.
- Photograph the dashboard while the light is on, so the mechanic or owner can see it.
- Ride gently to the nearest dealer or mechanic; do not dismantle or tamper with the fuel injection system yourself.
The Vision manual adds that if the starter turns but the engine will not start and the FI light is on, you should contact a Honda dealer as soon as possible, and that when the FI light is on the idling stop system is disabled to protect the engine. If a rental bike will not start, see also what to do when a rental motorbike will not start.
The ABS light: are the brakes still safe?
According to the Honda ADV160 manual, there may be a serious problem with the ABS if the light:
- Comes on or starts flashing while riding.
- Does not come on when the ignition is turned to On.
- Does not go off at speeds above 10 km/h.
In that case, reduce speed and have the bike checked soon. If the ABS light stays on, the brakes keep working as a conventional system but without the anti-lock function, so brake gently and earlier, especially on wet roads. The manual also mentions a harmless case: the ABS light may flash if the rear wheel is turned while the bike is on its stand; turn the key Off and On again and the light goes off once you reach 30 km/h. For braking without ABS, see our motorcycle braking technique guide.
Note: the Honda Vision uses combined braking, and the list of indicators in the Vision manual does not include an ABS light.
Coolant temperature and battery charging lights
The Honda ADV160 manual says the engine is overheating when the coolant temperature light comes on or acceleration becomes sluggish, and that continuing to ride an overheated engine can cause serious damage. Its procedure is:
- Pull safely to the side of the road and stop the engine with the ignition switch.
- Let the engine cool with the ignition switch Off.
- Inspect the radiator hose for leaks; if there is a leak, do not start the engine and transport the bike to a dealer.
- Check the coolant level in the reserve tank and add coolant if needed.
- If everything is normal, you may continue riding but keep a close eye on the temperature light.
The manual also notes that extended fast idling can make the temperature light come on. If the battery charging light comes on while riding, battery voltage may be low or the battery may be degrading, and the bike should be checked. If your bike has no temperature light (the Vision manual’s list of indicators does not include one), watch for the signs in our guide to a motorbike overheating on a trip.
Smart key, idling stop and oil change indicators
- Smart key light flashes 5 times: both the Vision and ADV160 manuals say to replace the key fob battery.
- Smart key light flashes while the switch is On (Vision): communication between the bike and the key has stopped, possibly because of strong radio waves or because the key was dropped while riding. The bike keeps working until the ignition is locked, so stop and check you still have the key before switching off.
- Idling stop light flashing (Vision): the engine has stopped itself at a halt; the manual says not to leave the bike while the light is flashing and always to turn the key Off when you walk away.
- Oil change indicator (ADV160): appears when the programmed oil change distance is reached and should be reset after the oil is changed.
If a warning light comes on during a rental, take a photo of the dashboard and follow our guide to reporting a problem with a rental motorbike. When you collect a bike from Mr Tú – Old Quarter Motorbike Rental, turn the key once and watch the lights do their self-check and go off.
Motorcycle warning lights FAQ
Is it a problem if the FI light comes on when I switch on?
No. According to the Honda Vision manual, the PGM-FI malfunction lamp comes on when the key is turned to On; before starting, confirm that it has gone off.
Can I keep riding with the FI light on?
Honda’s manuals advise reducing speed and having the bike inspected as soon as possible, because there may be a serious problem with the fuel injection system. Ride gently to the nearest workshop rather than continuing a long journey.
Do the brakes still work when the ABS light is on?
Yes. According to the Honda ADV160 manual, if the ABS light stays on the brakes work as a conventional system but without the anti-lock function; reduce speed and have the bike checked soon.
What does it mean when the smart key light flashes 5 times?
According to the Honda Vision and ADV160 manuals, it means the smart key fob battery needs replacing.
Sources: Honda Vietnam – Vision owner’s manual (indicators; troubleshooting: warning lights, idling stop system); Honda – ADV160 Owner’s Manual 2023 (Indicators; Warning Indicators On or Flashing; Overheating). Checked on 13/11/2026.
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