Why is my indicator flashing fast?

Because a bulb in that circuit has failed. Fast flashing, sometimes called hyperflash, is a designed-in warning: the flasher circuit senses the reduced electrical load when one lamp stops drawing current and doubles the rate so the driver notices. Check the front indicator, the rear indicator and the side repeater on that side. The other common cause is fitting LED bulbs in place of filament ones, because LEDs draw so little current that the circuit reads them as failed even though they are lit; that needs a load resistor or a bulb designed for a CAN-bus car.

Do indicators fail an MOT?

Very often. In the DVSA data behind this site, direction indicator lamp defects account for 105,791 recorded failures, which puts them among the biggest single causes of failure of any kind. Under section 4.4 an indicator that is missing, inoperative or the wrong colour is a major defect, as is a defective lens that affects the light emitted. The tester also checks the flash rate and that the lamps work from the driver's seat. It is a frustrating way to fail, because a bulb is one of the cheapest parts on the car and a two-minute walk round with someone operating the stalk would have caught it.

How fast should indicators flash?

Between 60 and 120 flashes per minute, which is the rate set by the lighting regulations and checked in the MOT. Anything obviously outside that, in either direction, is a defect. In practice a rate that is far too fast means a failed bulb on that side, and a rate that is far too slow usually points at a tired flasher relay, a poor earth or low battery voltage. A lamp that comes on and stays on without flashing at all is a failure of the flasher unit.

Why does my indicator tell-tale still tick but nothing flashes?

The audible side of the tell-tale is often generated by the car's speakers or a buzzer rather than by the flasher relay clicking, so on modern cars it will keep ticking cheerfully whether or not any lamp is actually lit. That is worth knowing, because it means you cannot rely on the sound to tell you the indicators are working. The MOT manual does accept an audible tell-tale as satisfying the requirement, but the lamps themselves are inspected separately.

Dashboard warning light

Indicator warning light

Last updated 27 July 2026

Quick answer

The indicator on that side is flashing. Nothing is wrong, and the accompanying tick is part of the same tell-tale — the MOT manual accepts an audible indicator tell-tale as well as a visual one. The one thing worth knowing is that if the arrow suddenly starts flashing at roughly double speed, a bulb on that side has failed.

What to do: No action needed
Can you drive?: Yes

Why it is green

Confirms something is switched on and working. Not a fault.

What turns it on

Operating the indicator stalk, or pressing the hazard switch, which flashes both arrows at once. The flash rate is set by the indicator relay or, on modern cars, by the body control module, and by regulation must fall between 60 and 120 flashes per minute.

What to do about it

If one side flashes noticeably faster than the other, walk round the car with the indicators on. Fast flashing is the deliberate warning that a bulb in that circuit has failed, and a dead indicator is a major MOT defect and an offence on the road.
If the arrow flashes fast after fitting LED bulbs, the LEDs draw too little current for the circuit to see them as working. The fix is a load resistor or a CAN-bus compatible bulb, not ignoring it.
If neither arrow flashes but the hazards work, suspect the stalk or its switch rather than the bulbs.
If the arrow stays on solid without flashing, the flasher unit or module has failed. The lamp on the road is probably lit constantly, which is worse than useless to other drivers.
Check the side repeaters too. They are part of the indicator system and easy to overlook because you never see them from the driver's seat.

Can you keep driving?

Yes

Yes when the tell-tale is behaving normally. If it is flashing fast you have a dead indicator bulb, and while the car will drive perfectly well, you are signalling to nobody on that side. That is an offence and a major MOT defect, and it is one of the cheapest and quickest faults on any car to put right.

What causes it

The indicator stalk has been operated — the ordinary case
The hazard switch is on, flashing both sides together
A blown indicator bulb on that side, which produces the fast flash
LED bulbs retrofitted into a circuit that monitors current draw
A failing flasher relay or body control module output, giving a solid or erratic tell-tale
Corrosion in a rear lamp cluster earth, which produces the odd cross-lit and half-speed symptoms indicators are famous for

Does it fail an MOT?

Not on its own — but what causes it often does.

The indicator tell-tale is a mandatory tell-tale, inspected under section 4.9.1, but a missing or inoperative one is only a minor defect — and it may be audible rather than visual, so a working tick satisfies the requirement. What fails cars in volume is the indicator lamps themselves, tested under section 4.4 for presence, condition, colour, security, switching and flash rate. Direction indicator lamp defects account for 105,791 failures in the DVSA data behind this site, making them one of the largest single groups of failures of any kind.

Common questions

Why is my indicator flashing fast?: Because a bulb in that circuit has failed. Fast flashing, sometimes called hyperflash, is a designed-in warning: the flasher circuit senses the reduced electrical load when one lamp stops drawing current and doubles the rate so the driver notices. Check the front indicator, the rear indicator and the side repeater on that side. The other common cause is fitting LED bulbs in place of filament ones, because LEDs draw so little current that the circuit reads them as failed even though they are lit; that needs a load resistor or a bulb designed for a CAN-bus car.
Do indicators fail an MOT?: Very often. In the DVSA data behind this site, direction indicator lamp defects account for 105,791 recorded failures, which puts them among the biggest single causes of failure of any kind. Under section 4.4 an indicator that is missing, inoperative or the wrong colour is a major defect, as is a defective lens that affects the light emitted. The tester also checks the flash rate and that the lamps work from the driver's seat. It is a frustrating way to fail, because a bulb is one of the cheapest parts on the car and a two-minute walk round with someone operating the stalk would have caught it.
How fast should indicators flash?: Between 60 and 120 flashes per minute, which is the rate set by the lighting regulations and checked in the MOT. Anything obviously outside that, in either direction, is a defect. In practice a rate that is far too fast means a failed bulb on that side, and a rate that is far too slow usually points at a tired flasher relay, a poor earth or low battery voltage. A lamp that comes on and stays on without flashing at all is a failure of the flasher unit.
Why does my indicator tell-tale still tick but nothing flashes?: The audible side of the tell-tale is often generated by the car's speakers or a buzzer rather than by the flasher relay clicking, so on modern cars it will keep ticking cheerfully whether or not any lamp is actually lit. That is worth knowing, because it means you cannot rely on the sound to tell you the indicators are working. The MOT manual does accept an audible tell-tale as satisfying the requirement, but the lamps themselves are inspected separately.

This is general guidance, not a diagnosis. Manufacturers draw the same system differently and reuse symbols for more than one function, so check the handbook for your own car before acting on anything here.

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