What causes the ABS light to illuminate in a Peugeot 308?

[VonKeira]

There are several conditions under which the ABS light may illuminate, each with different causes and solutions: Condition 1: ABS warning light stays on constantly (most common). Cause 1: The ABS speed sensor's sensing area is covered by mud, sludge, or other contaminants, affecting its ability to detect speed signals. This prevents the ABS computer from determining vehicle speed or wheel slip rate, thus failing to issue appropriate braking commands. Solution: Clean the speed sensor and adjust the gap between the sensor and the signal ring to restore normal function. Cause 2: Loose system wiring connections or poor ABS relay contact causing signal issues. Solution: Check all wiring connections and secure any loose connections. Condition 2: ABS warning light illuminates intermittently, turning off during acceleration. Cause: Battery voltage drops below 10.5V when multiple electrical components are in use. The light turns off when engine speed increases and voltage rises. Possible low voltage supply to ABS system due to poor connections or grounding. Solution: Check battery condition, charging system, and power supply (including voltage relay and connections). Condition 3: ABS warning light stays on after engine start until engine is turned off. Cause: Poor grounding of ABS hydraulic valve body; faulty wiring connections; or ABS computer malfunction. Solution: Loosen and retighten valve body grounding screws, clean contact surfaces if necessary; check for enlarged connector gaps; replace ABS or ABS/ASR computer if needed. Condition 4: ABS warning light illuminates during high-speed driving. Cause: ABS computer detects significant speed difference between front and rear wheels; incorrect tire or wheel specifications. Solution: Verify correct tire and wheel specifications as indicated on the fuel filler cap label. Condition 5: ABS warning light flashes intermittently. Cause: Improper brake light switch adjustment; internal contact issues in brake lights. Solution: With engine running, press brake pedal and manually push switch lever down completely, then release pedal to reset position; replace brake light switch if necessary. When the ABS warning light is on, it's recommended to avoid driving as this indicates a malfunction in the anti-lock braking system. During emergency braking, locked wheels could cause loss of vehicle control, preventing proper deceleration or steering adjustment, creating significant safety risks.

[MacRose]

I also had the ABS light issue with my Peugeot 308, which was quite annoying. There are usually several common causes. The most frequent one is a dirty or faulty wheel speed sensor—over time, dust and debris buildup can interfere with the signal, causing the ABS light to flash for no reason. Loose or corroded wiring connectors are another suspect, especially in older cars where aging wiring can lead to poor contact and false alerts. Malfunctions in the ABS control module or hydraulic unit are also common, particularly when the module ages or gets short-circuited due to moisture. If the wheel speed sensor ring is worn or cracked, it can trigger the alarm too. When the ABS light comes on, the system might fail, making braking prone to skidding or loss of control—super dangerous, especially when driving at high speeds in rain or snow. Every time I notice the light on, I first check if the sensors are clean, wiping the wheel speed sensor connectors with a damp cloth to see if there’s any dirt buildup. Sometimes, minor issues can be fixed with a little DIY. If that doesn’t work, it’s best to visit a dealership for a computer diagnosis—using an OBD tool to scan the trouble codes can pinpoint the exact issue. Don’t delay—safety first, and the ABS system shouldn’t be taken lightly. Regular maintenance checks on the sensor areas can effectively prevent such problems.

[LaHaven]

There are numerous reasons why the ABS light illuminates, requiring a systematic approach to eliminate possibilities. The primary suspect is often a faulty wheel speed sensor—dust, rust, or oil contamination on the sensor probe can send incorrect signals to the ECU unit, triggering the warning. Wiring issues are also common culprits, including loose connectors, aged or short-circuited wires, or even blown fuses; any interruption in the circuit can activate the light. Problems with the ABS module itself are frequent as well, such as damaged internal chips in the control unit or hydraulic pump failure, which disrupts braking balance. Another factor is damage or improper installation of the wheel speed sensor ring—if the reluctor ring on the hub is cracked or misaligned, it cannot accurately detect wheel speed. A constantly lit ABS light indicates the system may be disabled, and in extreme cases, hard braking could cause wheel lock-up, increasing accident risks—prompt diagnosis is essential. Using an OBD scanner to read trouble codes is the best way to pinpoint the root cause and avoid unnecessary part replacements. During routine maintenance, remember to clean the sensor areas under the chassis to prevent blockages. The illumination of this light can also be influenced by weather and road conditions, with slippery surfaces more likely to expose underlying faults.

[LeBrantley]

The ABS light on my Peugeot 308 has come on several times, usually due to dirty sensors or module failure. The wheel speed sensor is a critical component, embedded in the wheel and prone to dirt and rust, which can cause false alarm signals. Loose wiring connections or blown fuses are also common triggers. If the control unit is faulty, the light will stay on more frequently. Remember, once the light comes on, be alert as ABS system failure increases the risk of longer braking distances. Take it to a repair shop to read the fault codes and identify the issue promptly—don't delay.