The electronic stabilisation control (ESC) increases the car's stability. It reduces the tendency to skid and improves the stability and roadholding of the Audi A4. The ESC detects critical handling situations, such as understeer, oversteer and wheelspin on the driven wheels. It stabilises the Audi A4 by braking individual wheels or by reducing the engine torque. The indicator lamp 
in the instrument cluster starts flashing as soon as the ESC intervenes.
in the instrument cluster starts flashing as soon as the ESC intervenes.The following systems are integrated in the ESC:
Anti-lock brake system (ABS)
ABS prevents the wheels from locking up under braking until the Audi A4 has reached a virtual standstill. You can continue to steer the Audi A4 even when the brakes are on full. Keep your foot on the brake pedal and do not pump the brakes. You will feel the brake pedal pulsate while the anti-lock brake system is working.
Brake assist system
The brake assist system can shorten the braking distance. The braking force is automatically boosted if you press the brake pedal quickly in an emergency. You must keep pressing the brake pedal until the danger has passed. On Audi A4s with adaptive cruise control*, the response of the brake assist system will be more sensitive if you are too close to the Audi A4 in front.
Traction control system (ASR)
In the event of wheelspin, the traction control system reduces the engine torque to match the amount of grip available. This helps the car to start moving, accelerate or climb a gradient.
Electronic differential lock (EDL)
When the EDL detects wheelspin, it brakes the spinning wheel and directs the power to the other driven wheel (or wheels on quattro* versions). This function is not available at high speeds.
To prevent the disc brake of the braked wheel from overheating, the EDL cuts out automatically if subjected to excessive loads. The Audi A4 can still be driven. The EDL will switch on again automatically when the brake has cooled down.
Steering recommendation
The ESC helps to stabilise the Audi A4 by changing the steering wheel torque.
On Audi A4s with dynamic steering*, the ESC can also adjust the steering angle to stabilise the Audi A4 in critical situations.
Trailer stabilisation system*
Trailers have a tendency to sway. If the ESC detects that the trailer is swaying and this is affecting the towing Audi A4, it will automatically brake the Audi A4 in order to stabilise the trailer Link.
Electronic limited slip differential* / selective wheel torque control*
An electronic limited slip differential (front-wheel drive) or selective wheel torque control function (four-wheel drive) intervenes when cornering by braking the unladen wheel(s) on the inside of the bend individually as required. This enables precision cornering. The relevant system may not intervene in the wet or snow.
WARNING!
- The grip provided by the ESC and the integrated systems is still subject to the physical limits of adhesion. Always bear this in mind, especially on wet or slippery roads. If you notice the systems cutting in, you should reduce your speed immediately to suit the road and traffic conditions. Do not let the extra safety provided tempt you into taking any risks when driving – this can cause accidents.
- Remember that the accident risk always increases if you drive fast, especially in corners or on a wet or slippery road, or if you follow too close behind the Audi A4 in front of you. Please bear in mind that even the ESC and the integrated systems cannot compensate for the increased accident risk.
- When accelerating on a uniformly slippery surface (for instance all four wheels on ice or snow), press the accelerator gradually and carefully. The driven wheels may otherwise start to spin (in spite of the integrated control systems), which would impair the car's stability and could lead to an accident.
Note
- To ensure that the ABS and ASR systems work properly, all four wheels must be fitted with identical tyres. Any differences in the rolling radius of the tyres can cause the system to reduce engine power when this is not desired.
- The systems can make noises when they intervene.
- If the indicator lamp or
appears, there may be a malfunction Link.