Seven types of fault lights!
“Fault lights, often glowing ominously on our dashboards or control panels, are the unsung heroes of diagnostics. They’re tiny beacons of distress, alerting us to a problem that requires attention. Ignoring them can lead to further damage, costly repairs, or even dangerous situations. Understanding the different types of fault lights and what they signify is crucial for anyone operating a vehicle or machinery. Here, we’ll delve into seven common categories of fault lights, explaining their typical meanings and what steps you should take when they illuminate.
1. The Engine Management Light (EML) / Check Engine Light:
Perhaps the most universally recognized fault light, the Engine Management Light (often simply called the “Check Engine Light”) is a powerful indicator of issues within your vehicle’s engine or emissions system. When this light, typically an outline of an engine, illuminates, it means the onboard diagnostics (OBD-II) system has detected a fault. This fault could be anything from a loose gas cap (a surprisingly common culprit) to more serious problems like a failing oxygen sensor, a faulty catalytic converter, misfiring spark plugs, or an issue with the mass airflow sensor.
The EML can sometimes illuminate steadily, indicating a less urgent issue that still needs to be checked soon. However, if the EML is flashing, this is a critical warning that a severe problem, often a misfire that could damage the catalytic converter, is occurring. In such cases, it’s advised to pull over safely as soon as possible and have the vehicle inspected. A diagnostic scan tool is usually required to read the specific trouble codes stored in the vehicle’s computer, pinpointing the exact cause of the EML’s illumination.
2. The Oil Pressure Warning Light:
Represented by an oil can symbol, the oil pressure warning light is a critical indicator of your engine’s health. Engine oil is the lifeblood of your vehicle, lubricating moving parts and preventing excessive friction and heat. When this light illuminates, it signifies that the oil pressure is too low. This could be due to several reasons: insufficient oil levels, a faulty oil pump, a clogged oil filter, or a leak in the oil system.
Low oil pressure is not something to ignore. Continuing to drive with this light on can lead to severe engine damage, including seized components and complete engine failure. If the oil pressure light comes on, you should immediately and safely pull over, turn off the engine, and check your oil level. If the level is adequate, or if the light persists after topping up, do not drive the vehicle. It needs to be towed to a mechanic for professional diagnosis and repair.
3. The Battery Warning Light:
This light, depicted as a battery symbol, indicates a problem with your vehicle’s charging system, not necessarily the battery itself. While a dead battery will prevent your car from starting, the battery warning light typically illuminates while the engine is running, signaling that the alternator is not generating enough power to recharge the battery or power the electrical system.
The alternator is responsible for converting mechanical energy from the engine into electrical energy. If it’s failing, the battery will eventually drain, leading to a loss of electrical power and the vehicle ultimately stalling. Other causes could include a loose or broken alternator belt, faulty wiring, or an issue with the voltage regulator. If this light comes on, you might notice other electrical components (like headlights or radio) dimming. It’s advisable to get to a service center as soon as possible to avoid being stranded.
4. The Brake System Warning Light:
Often represented by an exclamation mark within a circle, or the word “BRAKE,” this light can signify a few different issues related to your vehicle’s braking system. One of the most common reasons for its illumination is the activation of the parking brake. Always check if your parking brake is fully disengaged when this light is on.
If the parking brake is not engaged, the light could indicate low brake fluid levels. Brake fluid is essential for transmitting the force from your brake pedal to the brake calipers, enabling the car to stop. Low fluid levels can be caused by worn brake pads (as the calipers extend, more fluid is needed to fill the system) or a leak in the brake lines. A persistent brake warning light also might indicate a problem with the hydraulic braking system itself, such as a faulty master cylinder. Given the critical safety role of brakes, this light demands immediate attention from a qualified mechanic.
5. The Anti-lock Braking System (ABS) Warning Light:
The ABS warning light, usually showing the letters “ABS” within a circle, indicates a fault within the anti-lock braking system. The ABS prevents the wheels from locking up during hard braking, allowing the driver to maintain steering control. Unlike the main brake warning light, the illumination of the ABS light does not mean your regular brakes have failed. Your conventional braking system should still function.
However, if the ABS light is on, the anti-lock function will not be operational. This means that in an emergency braking situation, your wheels could lock up, and you might lose steering control. Common causes for an illuminated ABS light include faulty wheel speed sensors (which monitor the rotation of each wheel), a problem with the ABS module, or low brake fluid. While less immediately critical than a regular brake warning, it’s still important to have your ABS system checked for safety reasons.
6. The Tire Pressure Monitoring System (TPMS) Light:
Depicted as a cross-section of a tire with an exclamation mark inside, the TPMS light indicates that one or more of your vehicle’s tires are significantly underinflated. Modern vehicles are equipped with TPMS to enhance safety and fuel efficiency. Underinflated tires can lead to reduced fuel economy, premature tire wear, and an increased risk of a blowout, especially at high speeds.
When this light comes on, you should check the pressure of all your tires as soon as possible and inflate them to the manufacturer’s recommended specifications (usually found on a sticker inside the driver’s side door jamb or in the owner’s manual). If the light remains on after inflating the tires, there might be a slow leak that needs professional repair, or a fault with one of the TPMS sensors themselves. Some TPMS lights might flash initially, indicating a sensor malfunction, and then stay solid, indicating low pressure.
7. The Airbag / SRS Warning Light:
Represented by a symbol of a person with a deployed airbag (often with the letters “SRS” for Supplemental Restraint System), this light indicates a fault within your vehicle’s airbag system. The SRS includes not just the airbags, but also the seatbelt pretensioners and associated sensors and wiring. The system is designed to deploy airbags in the event of a collision, providing crucial protection to occupants.
If this light illuminates, it means that in the event of an accident, the airbags or seatbelt pretensioners might not deploy as intended, or they could even deploy accidentally. This is a significant safety concern. Causes can range from faulty sensors, wiring issues, a problem with the SRS control module, or even a faulty clock spring in the steering wheel. As this system is vital for occupant safety, it’s imperative to have an illuminated airbag light diagnosed and repaired by a professional immediately.
Conclusion:
Fault lights are not just annoyances; they are vital communication tools from your vehicle or machinery. They provide early warnings that, when heeded, can save you from more extensive damage, higher repair costs, and potentially dangerous situations. While some lights, like the TPMS, might allow for a self-fix, many others, particularly those related to the engine, brakes, or safety systems, require professional diagnosis and repair. Understanding these seven common types of fault lights empowers you to react appropriately, ensuring the longevity and safe operation of your equipment. Always consult your owner’s manual for specific details about the fault lights in your particular model.