Warning lights of the Audi A5: what each light means
In the 2 generations of the Audi A5, the documented faults light up 6 warning lights on the dashboard. The most frequent: engine warning light (5 faults), overheating (3 faults) and airbag light (2 faults). Overheating and oil warning light call for stopping as soon as possible.
Which warning lights the faults of the Audi A5 trigger
Red ones first, and those that call for stopping. Below each warning light, the documented faults that trigger it, with their pages.
Overheating or temperature warning light
Urgency: As soon as possibleRedSymbol: thermometer over wavy lines (coolant)
The temperature needle climbs towards the red zone or the coolant warning light comes on. It usually points to a lack of coolant, a leak, or a failing thermostat or water pump. Driving on can warp the cylinder head or damage the gasket.
What to do: Stop as soon as you can and switch the engine off. Do not open the coolant reservoir cap while it is hot. If coolant is missing, do not set off again until you have found the leak.
3 documented faults that trigger it in the Audi A5
- High severity: Failing water pump and cooling system leaks · 3.0 TDI V6 engine · I and II
- Medium severity: Thermostat housing leak and water pump failure · 2.0 TSI / TFSI engine · I
- Medium severity: Leak at the thermostat housing and water pump · Audi 3.0 TFSI V6 engine · I
Oil pressure warning light on
Urgency: As soon as possibleRedSymbol: oil can (an oil can with a drop)
The red oil-can warning light means the engine is not getting the oil pressure it needs. The cause may be a low oil level, a failing oil pump or a blocked oil circuit. With low pressure, parts such as the turbo, the bearings or the timing drive can wear out within minutes.
What to do: Stop the car as soon as it is safe and switch the engine off. Check the level with the dipstick and do not drive on if the light stays on: call a recovery truck.
1 documented fault that triggers it in the Audi A5
- High severity: High oil consumption · 2.0 TSI / TFSI engine · I
Airbag warning light on
Urgency: Garage soonRedSymbol: a seated person wearing a seat belt with a circle (the inflated airbag) in front; in some cars, the letters SRS or AIRBAG
The airbag warning light means the system has detected a fault and an airbag or seatbelt pretensioner may not deploy in a crash. Causes range from a connector under the seat to the control unit or the airbag itself.
What to do: Have it diagnosed as soon as possible and check with the VIN whether the car has any outstanding airbag recall.
2 documented faults that trigger it in the Audi A5
- High severity: Passenger airbag module screw not tightened properly · outside the engine · II
- High severity: Damaged transistor in the airbag control unit on units from May 2019 · outside the engine · II
Engine fault warning light (check engine)
Urgency: Garage soonYellow or amberSymbol: outline of an engine seen from the side, in yellow or orange
The orange engine-shaped warning light comes on when the ECU detects a fault affecting combustion or emissions. If it flashes, it usually points to misfires that can damage the catalytic converter.
What to do: If it stays on steadily, you can drive gently to a garage and ask for a fault code read-out. If it flashes or you notice a loss of power, slow down and get to a garage as soon as possible.
5 documented faults that trigger it in the Audi A5
- Critical severity: Timing chain and tensioner wear · 2.0 TSI / TFSI engine · I
- Medium severity: Carbon build-up on the intake valves · 2.0 TSI / TFSI engine · I
- High severity: Injector wear (needle seat) and injection faults · 3.0 TDI V6 engine · I and II
- Low severity: PCV valve (crankcase ventilation) failure · 2.0 TSI / TFSI engine · I
- Low severity: PCV valve failure (crankcase ventilation) · Audi 3.0 TFSI V6 engine · I
ABS or ESP warning light on
Urgency: Garage soonYellow or amberSymbol: the letters ABS, usually inside a circle, in amber or orange
It indicates a fault in the anti-lock braking or stability control system: often a dirty or damaged wheel speed sensor, its wiring or the hydraulic unit. The brakes still work, but without those aids.
What to do: Drive carefully, especially in the rain, and ask for a fault code read-out. It is often fixed with a wheel sensor.
1 documented fault that triggers it in the Audi A5
- Low severity: MMI screen, radio and on-board electronics faults · outside the engine · I
ESP warning light on or flashing
Urgency: Garage soonYellow or amberSymbol: the silhouette of a car with curved skid marks (swerving lines) beneath it, or the letters ESP, in amber or orange
The ESP light belongs to the electronic stability control, the system that brakes wheels individually and reduces power when the car starts to skid. It flashes while the system is intervening; if it stays on steadily, it usually indicates a fault (often a sensor) or that ESP has been switched off with its button.
What to do: If it flashes in a bend or on a wet road, ease off: ESP is working. If it stays on, switch off and restart, check the ESP OFF button has not been pressed and, if it persists, ask a garage for a fault code read-out.
1 documented fault that triggers it in the Audi A5
- Low severity: MMI screen, radio and on-board electronics faults · outside the engine · I
Frequently asked questions
Which warning lights come on most in the Audi A5?
Engine warning light: 5 documented faults, such as timing chain and tensioner wear. Overheating: 3 documented faults, such as failing water pump and cooling system leaks. Airbag light: 2 documented faults, such as passenger airbag module screw not tightened properly.
Which warning light of the Audi A5 is the most serious?
Overheating and oil warning light: its urgency is “as soon as possible”. Stop the car as soon as it is safe; on each warning light's page, at the top, you will find what to do.
Which generation of the Audi A5 has the most faults that trigger warning lights?
Audi A5 I (11 faults) and Audi A5 II (4 faults).
A warning light has come on in the Audi A5: what should I do?
Find which warning light it is on this page and check its urgency. With overheating and oil warning light, stop as soon as possible somewhere safe. For the others, book an appointment at a garage and have them read the fault code with an OBD reader: it shows which system has failed.