Understanding dashboard warning lights in your Audi S4 is essential for keeping you safe on the road and avoiding costly repairs. These lights alert you to potential issues early, helping prevent breakdowns or accidents by prompting timely action.
By knowing what each one means, you can maintain your vehicle’s performance and respond quickly to problems.
Quick Navigation
Red Warning Lights (Stop Immediately)
Brake System Alert
Low brake fluid or a fault in the brakes. Pull over safely right away, check fluid levels, and call a mechanic if needed to avoid losing braking power.
Engine Oil Pressure
Low oil pressure that could damage the engine. Stop the car immediately, turn off the engine, check oil level, and add more if low; get help if it stays on.
Battery Charge
Battery not charging properly due to alternator issues. Stop driving soon as the car may lose power; check connections and seek a service center for repairs.
Airbag System
Fault in airbags or seat belt tensioners. Stop and have it checked at a service center to ensure safety features work in a crash.
Coolant Temperature
Engine overheating from low coolant or a cooling fault. Pull over, let the engine cool, check coolant, and avoid driving until fixed.
Seatbelt Reminder
Seatbelt not fastened for driver or passengers. Stop and buckle up before continuing to drive.
Power Steering Failure
Issue with power steering making handling hard. Stop safely and contact a service center; do not drive far.
Bonnet Open
Hood not closed properly. Pull over and secure the hood to prevent it from opening while driving.
Door Ajar
A door not fully closed. Stop and close all doors securely before proceeding.
AdBlue Low
AdBlue fluid critically low in diesel models. Refill immediately or the engine may not start; stop and add fluid.
Steering Lock Malfunction
Electronic steering lock failed. Do not turn off the engine; drive to a service center as you may not restart.
Key System Fault
Problem with the key or start system. Stop and seek help; engine may not restart if turned off.
Brake Fluid Low
Brake fluid level too low. Pull over, check and top up fluid, then visit a mechanic if it persists.
Transmission Overheat
Transmission too hot from heavy use. Stop and let it cool; avoid driving until checked.
Engine Overheat
General engine temperature too high. Stop immediately, turn off engine, and inspect for causes like leaks.
Yellow/Amber Warning Lights (Action Required Soon)
Check Engine
Engine or emissions issue like a sensor fault. Drive carefully and visit a service center soon for diagnosis.
Tire Pressure Monitoring
Tire pressure low or uneven. Check and inflate tires to recommended levels; inspect for punctures.
ABS System
Anti-lock brake system fault. Brakes still work but without anti-skid; get it serviced soon.
Glow Plug (Diesel)
Issue with diesel engine warm-up. Check for faults and service if it flashes; safe to drive short distances.
ESP Stability Control
Electronic stability program not working. Drive with caution on slippery roads; schedule a check.
Transmission Fault
Gearbox or clutch problem. Reduce speed and get to a service center for repairs.
DPF Filter
Diesel particulate filter clogged. Drive at higher speeds to regenerate or visit a mechanic.
Coolant Level Low
Coolant below safe level. Top up coolant and check for leaks; monitor closely.
Brake Pad Wear
Brake pads worn thin. Replace pads soon to maintain stopping power.
Fuel Filter (Diesel)
Water in fuel filter. Drain water and replace filter if needed; service promptly.
Lane Departure Warning
Lane assist system inactive or faulty. Clean sensors and reactivate; service if needed.
Exhaust System
High emissions or catalytic converter issue. Drive to a service center for emissions check.
Green Lights (Information Only)
Eco Mode Engaged
Fuel-saving mode activated for better efficiency. Continue driving; switch off if desired.
High Beam On
Headlights on high beam. Adjust to low beam when needed to avoid blinding others.
Cruise Control Active
Cruise control set and maintaining speed. No issue; adjust or turn off as required.
Turn Signal Indicator
Blinker active for turning. Turns off automatically after maneuver.
Front Fog Lights On
Fog lights activated for better visibility. Turn off when conditions improve.
Rear Fog Lights On
Rear fog lights in use. Deactivate when no longer foggy.
Parking Lights On
Side lights active. Normal when parked or in low light.
Adaptive Headlights Active
Headlights adjusting to road conditions. System functioning as intended.
Rain Sensor Active
Automatic wipers detecting rain. No action; it’s operating correctly.
Hill Hold Assist On
System holding brakes on inclines. Releases when accelerating.
Auto Hold Active
Brakes held automatically at stops. Press accelerator to release.
Dynamic Mode Engaged
Performance driving mode selected. Switch modes as preferred.
Seat Heater On
Seat heating activated. Adjust temperature or turn off.
Windshield Defrost Active
Defroster clearing windshield. Turns off when clear.
When looking at Audi, make sure to check out our guides on models like the Audi S5, Audi SQ8, Audi SQ7, and Audi SQ5. Understanding dashboard warning lights is essential. Our expert reviews break down what each light means, highlighting common alerts for these models and what they could signal about underlying issues, so you’re never left guessing behind the wheel.
