Icon "A in a circle" with or without an exclamation markappearing on the dashboard indicates a malfunction in anti-lock brake system (ABS) or related components. By car Volkswagen, Audi, Škoda, Seat and other brands of the group VAG This icon often lights up when there is a malfunction of the wheel sensors, damaged wiring or a malfunction of the ABS control unit. In some models (for example, Ford Focus or Renault Megan) a similar symbol may indicate problems with stabilization system (ESP) or anti-skid system (ASR), if it is combined with other indicators.
If icon flashes when moving, this usually indicates a temporary failure (for example, icing of the sensors or contamination). Constantly lit icon is a sign of a serious problem that requires diagnosis. Ignoring the signal may result in ABS failure in a critical situation, although the main brakes will remain operational. Next, we’ll look at how to accurately determine the cause based on the car model, what error codes to look for, and what to do to fix the problem.
What does the “A in a circle” icon look like and where to look for it
The icon represents a letter «A» (sometimes stylized as «ABS»), enclosed in a circle. Depending on the manufacturer and year of manufacture of the car, it may differ in details:
- 🔴 Red color - critical ABS malfunction (requires immediate stop and inspection).
- 🟡 Yellow/orange color — warning about a malfunction of the stabilization system or traction control system.
- ❄️ Snowflake or water drops next to the icon - problems may occur due to low temperatures or moisture (for example, icing of sensors).
- ⚡ Lightning inside or nearby - there is a malfunction in the ABS electrical circuit.
On most cars the icon is located in right side of the dashboard, next to the indicators ESP, Check Engine or brake system. On some models (for example, BMW or Mercedes-Benz) instead of the letter “A” the full inscription may be displayed «ABS» in a circle.
Where to look for the icon on popular models
On Volkswagen Golf/Polo (2010–2023) the icon appears to the right of the speedometer, below the fuel indicator. B Toyota Corolla (2018+) - in the central part of the panel, next to the handbrake symbol. On Hyundai Solaris/Kia Rio the icon may be combined with an exclamation point in brackets if the problem also affects the brake system.
Reasons for the appearance of the “A in a circle” icon by car brand
The list of possible faults varies depending on the manufacturer and year of manufacture. Below are the most common reasons for popular brands:
| Make/Model | Common reasons | Additional symptoms |
|---|---|---|
| Volkswagen/Audi (2010–2023) | Malfunction of the ABS sensor on the rear wheel, corrosion of the connectors | Lights up with ESP, possible jerking when braking |
| Ford Focus/Mondeo (2015–2022) | Damage to the wiring to the sensors, malfunction of the ABS unit | The icon flashes at speeds above 40 km/h |
| Renault Duster/Logan (2014–2021) | Sensor contamination or open circuit | Accompanied by a squeaking sound when starting the engine |
| Toyota RAV4/Camry (2018+) | Malfunction of the ABS hydraulic unit | The brake pedal becomes “wobbly” |
On vehicles with start-stop system (for example, Mazda CX-5 or Peugeot 3008) the icon may light up when the battery is discharged, since ABS requires a stable voltage. In hybrid models (for example, Toyota Prius) the cause is often a malfunction regenerative braking systemrelated to ABS.
Exclamation mark|Lightning|Snowflake|No additional marks|I don’t know-->
Fault diagnosis: step-by-step instructions
To determine exactly why the icon appears, follow these steps:
- Check the brake fluid level - a low level can cause false activation of the ABS sensors.
- Inspect the wheel sensors for contamination or damage. The most vulnerable sensors rear wheels (especially on VAG-group).
- Reset the error by disconnecting the battery for 10–15 minutes (does not always help with hardware faults).
- Connect diagnostic scanner (for example, ELM327 or Launch CReader) to read error codes.
If the icon appears again after resetting the error, the problem is hardware character. In this case, you will need to check:
- 🔌 Postings from ABS sensors to the control unit (often frays at bending points).
- 🛠️ Ring gear on the wheel hub (if damaged, the sensor does not read the signal).
- 💻 ABS control unit (may fail due to moisture or overheating).
Brake fluid level checked|ABS sensors inspected for contamination|Error cleared by disconnecting the battery|Error codes recorded by scanner (if any)|ABS fuses checked (usually F30 or F31)-->
Deciphering ABS error codes
When diagnosing with a scanner, you may encounter the following codes (these are common to most brands):
| Error code | Meaning | What to check |
|---|---|---|
C0035, C0040 |
Front/rear ABS sensor malfunction | Wiring condition, sensor cleanliness, ring gear |
C0110 |
Problems with the ABS hydraulic unit | Brake fluid leaks, pump operation |
U0121 |
Lost communication with ABS control unit | Fuses, connectors, CAN bus |
C0200 |
Incorrect wheel speed sensor signal | Sensor contamination, wheel bearing play |
By car BMW and Mercedes-Benz codes may have a different format (for example, 5E20 for a malfunction of the rear right wheel sensor). For accurate decryption, use service manuals specific model or software of diagnostic equipment (for example, ISTA+ for BMW).
⚠️ Attention: If the indicator lights up along with the “A in a circle” icon brake system (red exclamation point), the vehicle must not be driven - this may indicate a brake fluid leak or a failed master cylinder.
What to do if the icon lights up on the way
If the icon appears while driving, follow these steps:
- Don't panic — ABS does not affect the operation of the main brakes, but can increase the braking distance on slippery roads.
- Reduce speed and avoid sudden maneuvers, as the stability control system (ESP) may be disabled.
- Check the brakes on a safe section of the road - if the pedal becomes soft or the travel increases, stop immediately.
- If possible, reset the errorby turning the ignition off and on (sometimes it helps with temporary failures).
If icon does not go out after restarting the engine, continue driving to the nearest service station, avoiding off-road conditions and sudden braking. On vehicles with electronic hand brake (for example, Volkswagen Tiguan) A faulty ABS can prevent it from working - be prepared to use the parking brake manually.
On some models (for example, Ford Kuga) you can temporarily disable the warning by pressing and holding the button ESP Off within 5 seconds. However, this does not eliminate the cause of the malfunction!
The cost of repairs and is it possible to drive with an “A in a circle” badge?
The cost of troubleshooting depends on the cause:
- 🔧 Cleaning ABS sensors — from 500 to 1,500 rubles. (you can do it yourself).
- 🔌 Replacing wiring — 2,000–5,000 rub. (depending on model).
- 🛠️ Replacing the ABS sensor — 1,500–4,000 rub. for one sensor + work.
- 💻 Repair/replacement of ABS unit — 10,000–30,000 rub. (premium brands are more expensive).
Drive with the “A in a circle” badge you can, but with caution:
- ✅ It is allowed to move around the city at a moderate speed.
- ❌ It is prohibited to drive off-road or in icy conditions - ABS will not work.
- ⚠️ On cars with brake force distribution (EBD) system Possible uneven wheel braking.
⚠️ Attention: On some models (for example, Audi A4 B8) long-term driving with faulty ABS can lead to ESP blocking and engine emergency mode (power limitation).
Even if the brakes work normally, ignoring the “A in a circle” icon may lead to the failure of the stabilization system in a critical situation (for example, when avoiding an obstacle).
How to prevent the icon from appearing in the future
To minimize the risk of the indicator triggering again, follow the recommendations:
- 🚿 Wash the wheel arches in winter - salt and reagents cause corrosion of sensors.
- 🔋 Keep an eye on your battery - Low voltage can cause electronic malfunctions.
- 🛞 Check wheel bearing play - it leads to incorrect sensor readings.
- 🔧 Get your ABS diagnosed regularly (once every 30,000 km) at stations with professional equipment.
On vehicles with air suspension (for example, Mercedes-Benz S-Class) ABS failures may be caused by a malfunction of the ground clearance control system. In this case, a comprehensive diagnosis of the chassis is required.
If you often drive off-road, install protective covers on the ABS sensors - this will prevent them from being damaged by stones or dirt. On some models (for example, Toyota Land Cruiser) such covers come complete with the factory body kit.
FAQ: Frequently asked questions about the “A in a circle” icon
Is it possible to reset the ABS error yourself without contacting service?
Yes, you can temporarily reset the error by disconnecting the battery for 10–15 minutes or using a diagnostic scanner (for example, ELM327 with the program Torque Pro). However, if the problem persists, the icon will appear again. On some vehicles (for example, BMW) Resetting requires specialized software.
The "A in a Circle" and "Check Engine" icons came on at the same time - what is the reason?
The combination of these indicators often indicates problems with wheel speed sensors or ABS control unitthat affect engine operation (for example, through the stabilization system). On vehicles with cruise control or adaptive cruise (for example, Volvo XC60) this may disable these features. Immediate diagnosis is recommended.
Could the "A in a circle" icon light up due to a faulty battery?
Yes, especially on modern cars with a lot of electronics. At low voltage (less than 11.8 V), the ABS control unit may generate false errors. Check the battery voltage with a multimeter and charge or replace it if necessary. On hybrid vehicles (eg Toyota Prius) similar symptoms are caused by the discharge of a high-voltage battery.
What should I do if the icon only flashes at speeds above 60 km/h?
This is a typical sign malfunction of the ABS sensor on one of the wheels or ring gear damage on the hub. When the speed increases, the control unit does not receive a stable signal from the sensor, which leads to flashing. Check the sensors for dirt or play, and also inspect the rims for chips.
Can the "A in Circle" light come on due to winter tires or chains?
Yes, but only indirectly. If the chains or studs on winter tires damage ring gear hub, this may cause malfunction of the ABS sensors. Also on some vehicles (for example, Subaru Forester) icon may light up when discrepancy between wheel sizes (for example, if there are different disks on the front and rear axles).