Brake and ABS Lights On Together - Top Causes, Fixes & What to Do

Certified Professional Automotive Mechanic – Owner and Editor of VehicleRuns

Last Updated: August 18, 2026

Safety note: Troubleshooting guidance can help you narrow down likely causes, but it cannot replace an in-person inspection. If the vehicle feels unsafe, warning lights are flashing, you smell fuel, see smoke, notice overheating, or have problems with braking, steering, or control, stop driving when it is safe to do so and have the vehicle inspected.

When the brake warning light and ABS light come on together, the car is telling you there may be a problem in the braking system, the ABS control system, or both. Sometimes the cause is as simple as low brake fluid. Other times it points to a failed wheel speed sensor, an electrical fault, or a hydraulic problem that can affect how the brakes work.

The most useful first question is whether the car still feels normal when braking. If the pedal feels soft, the car pulls, braking distance increases, or you also see fluid loss, treat it as a more serious issue than a light-only fault.

This guide helps you narrow it down by matching the warning lights to what the brake pedal feels like, whether another warning light is present, and whether the problem showed up after recent brake work or during normal driving.

Start with how the brake pedal feels and whether the fluid level is low. A normal-feeling brake pedal often points to an ABS control fault, while a warning light plus poor braking feel can mean a hydraulic problem.

What you notice	Most likely cause	What to check first	Urgency
Both lights on, pedal feels normal	Wheel speed sensor fault	Scan ABS codes and inspect the affected wheel sensor area	Diagnose soon
Both lights on, fluid reservoir low	Brake fluid leak or pad wear	Check fluid level, then inspect calipers, hoses, and master cylinder	Can worsen
Both lights on, soft or sinking pedal	Hydraulic brake problem	Stop driving and inspect for leaks or master cylinder failure	Stop driving
Lights came on after brake work	Air in system or sensor issue	Check wheel sensor wiring and confirm the brake system was bled properly	Can worsen
ABS activates at low speed unexpectedly	Tone ring or wheel sensor fault	Inspect tone ring damage and sensor gap at each wheel	Can worsen

Best first move: If braking still feels normal, scan the ABS module first and check fluid level before replacing parts.

Safety note: Do not keep driving if the pedal is soft, the car pulls, the fluid level keeps dropping, or the red brake light stays on with poor braking performance.

Table of Contents

Most Common Causes of Brake and ABS Lights On Together

A few faults account for most cases where these two lights appear together. The three below are the most common starting points, and a fuller list of possible causes appears later in the article.

Low Brake Fluid Level: Low fluid can trigger the red brake warning light and may also disable ABS operation, especially if the level dropped because of pad wear or a leak.
Faulty Wheel Speed Sensor: A failed sensor or damaged tone ring is one of the most common reasons the ABS light comes on, and some vehicles will also turn on the brake warning light.
ABS Hydraulic Control Unit Fault: When the ABS module or hydraulic unit sees an internal fault, it can illuminate both lights and store ABS-specific trouble codes.

What Brake and ABS Lights On Together Usually Mean

When these lights come on together, the car has usually detected either a brake system warning and an ABS fault at the same time, or one fault serious enough to disable ABS and trigger the general brake warning. The exact meaning depends on the vehicle, but it almost always deserves attention soon.

If the brake pedal still feels firm and the car stops normally, the problem is often in the ABS side of the system. That includes wheel speed sensors, tone rings, wiring, or the ABS control unit. In that case, normal base braking may still work, but anti-lock braking and sometimes traction or stability functions may be reduced or disabled.

If the pedal feels soft, sinks at a stop, or the fluid reservoir is low, think hydraulic problem first. Low fluid, an external leak, air in the lines, or a failing master cylinder can turn on the brake warning light and may also bring the ABS light on because the control system sees a pressure or circuit problem.

Pattern matters. A warning that appears right after brake or hub work often points to a disturbed wheel speed sensor or trapped air. A warning that comes and goes over bumps can point to wiring or connector issues. A warning that is paired with false ABS activation at low speed strongly suggests a wheel speed sensor or tone ring problem at one wheel.

Possible Causes of Brake and ABS Lights On Together

Low Brake Fluid Level

The red brake warning light is commonly tied to the fluid level switch in the reservoir. When the level drops far enough, the car may also set ABS faults or disable ABS because the system sees a brake hydraulic issue.

Symptoms to Watch For

Fluid level below the MIN mark
Brake pedal travel slightly longer than normal
Brake pad wear visible at one or more wheels
Warning lights may come and go on hills or during turns

Moderate to High Severity

Low fluid can be caused by normal pad wear, but it can also mean an active leak that reduces braking safety.

How to Confirm: Check the brake fluid reservoir on a level surface.

How to Find a Brake Fluid Leak

Typical fix: Repair any leak, replace worn brake components as needed, and refill and bleed the brake system with the correct fluid.

Faulty Wheel Speed Sensor

ABS relies on accurate wheel speed data from each corner. If one sensor drops out, reads erratically, or loses its signal, the ABS module will often turn the ABS light on and may also illuminate the brake warning light on some vehicles.

Symptoms to Watch For

ABS light and brake light appear with otherwise normal braking
Traction or stability control light may also come on
False ABS activation at very low speed
Intermittent warning after rain, bumps, or wheel bearing work

Moderate Severity

Base brakes often still work, but ABS and stability functions may be unavailable when you need them most.

How to Confirm: Scan the ABS module for wheel speed sensor codes, then view live wheel speed data during a road test.

Typical fix: Replace the failed wheel speed sensor and repair any damaged wiring or connector at that wheel.

Damaged Tone Ring

The wheel speed sensor reads a tone ring or encoder. If the ring is cracked, rusty, dirty, or shifted out of place, the sensor signal becomes erratic and the ABS module may shut the system down and turn both lights on.

Symptoms to Watch For

False ABS engagement just before stopping
Intermittent ABS warning at low speed
Recent axle, hub, or bearing work
Visible rust swelling or cracked reluctor ring

Moderate Severity

This usually does not remove normal braking, but it can cause unstable ABS operation and poor low-speed stops.

How to Confirm: Inspect the tone ring or encoder on the affected wheel or axle after identifying the wheel with a scan tool or live data.

Typical fix: Replace the damaged tone ring, axle, or hub assembly depending on how the encoder is built into the vehicle.

External Brake Fluid Leak

A leak lowers fluid level and can introduce air into the system, which turns on the brake warning light. If pressure or hydraulic performance changes enough, the ABS system may also flag a fault.

Symptoms to Watch For

Soft or sinking brake pedal
Fluid loss over days or weeks
Wet brake hose, line, caliper, or backing plate
Brake warning appears with reduced stopping confidence

High Severity

Any active brake fluid leak can reduce braking ability and may worsen suddenly.

How to Confirm: Inspect the entire brake system for wetness, paying close attention to calipers, wheel cylinders, flexible hoses, steel lines, junctions, and the master cylinder area.

How to Find a Brake Fluid Leak

Typical fix: Replace the leaking hose, line, caliper, wheel cylinder, or master cylinder, then refill and bleed the system.

Failing Master Cylinder

A master cylinder with internal seal bypass can create a sinking pedal without an external leak. The red brake light may appear because braking performance is compromised, and ABS faults may follow if the module sees pressure problems or abnormal operation.

Symptoms to Watch For

Pedal slowly sinks while holding pressure
No obvious external leak
Brake warning with inconsistent pedal height
Fluid level may remain normal

High Severity

A failing master cylinder can sharply reduce predictable braking and should not be ignored.

How to Confirm: With the engine running, apply steady pressure to the brake pedal.

How to Diagnose a Bad Brake Master Cylinder

Typical fix: Replace the master cylinder and bleed the hydraulic system thoroughly.

ABS Hydraulic Control Unit Fault

The ABS hydraulic control unit contains valves, a pump, and electronics that manage anti-lock braking. Internal faults can store ABS module codes and turn on both the ABS and brake warning lights even when the base brakes still seem normal.

Symptoms to Watch For

Both lights stay on continuously
ABS-related trouble codes in the module
No obvious wheel sensor problem
Problem may appear after low voltage or internal module failure

Moderate to High Severity

The car may still stop, but ABS function is compromised and repair can become more expensive if misdiagnosed.

How to Confirm: Scan the ABS module for internal fault codes, pump motor codes, or valve circuit codes.

How to Diagnose an ABS Hydraulic Control Unit Problem

Typical fix: Replace or rebuild the ABS hydraulic control unit or module and perform any required programming and bleed procedure.

Wiring, Connector, or Electrical Ground Fault

ABS sensors and modules depend on clean power, ground, and signal wiring. Corrosion, broken wiring near a wheel, or a poor ground can trigger ABS faults and sometimes the brake warning light, especially if the issue affects reference voltage or module operation.

Symptoms to Watch For

Warning lights come and go over bumps
Problem started after suspension or brake work
Corrosion in connectors or damaged harness insulation
Multiple ABS-related codes that do not point to one clean failure

Moderate Severity

Electrical faults may not change pedal feel right away, but they can disable ABS and create hard-to-trace intermittent warnings.

How to Confirm: Inspect the harness at each wheel, near the struts, and at the ABS module for chafing, corrosion, or pulled wires.

Typical fix: Repair damaged wiring, clean or replace corroded connectors, and restore proper grounds.

How to Diagnose the Problem

Confirm whether the red brake warning light and the ABS light are both on steadily or only intermittently.
Check how the brakes feel before anything else. A soft pedal, sinking pedal, pull, or poor stopping feel moves this into a higher-risk category.
Inspect the brake fluid reservoir and note whether the level is below MIN, just above MIN, or normal.
Look for obvious leaks at each wheel, along the brake lines and hoses, and around the master cylinder and booster area.
If the fluid level is normal and braking feels normal, scan the ABS module for stored codes instead of guessing from the dash lights alone.
Read live wheel speed data during a low-speed road test if your scan tool allows it. Watch for one wheel that drops out or reads differently from the others.
Inspect the suspected wheel speed sensor area for damaged wiring, rust buildup, loose mounting, or tone ring damage.
If the problem started after recent brake, hub, axle, or bearing work, recheck sensor routing, connector seating, and proper component installation at that corner.
If codes point to pump motor, valve, or internal module faults, verify battery voltage, grounds, and power feeds before replacing the ABS unit.
Stop driving and arrange repair if you find fluid loss, a sinking pedal, or any sign that basic braking is affected.

Can You Keep Driving with the Brake and ABS Lights On Together?

Important: The guidance below is general and cannot confirm that your specific vehicle is safe to drive. If a symptom affects braking, steering, handling, fuel, overheating, smoke, visibility, or vehicle control, treat it as potentially serious and have the vehicle inspected before continued driving when appropriate. For more context, see our Automotive Safety Disclaimer.

Whether you can keep driving depends less on the lights themselves and more on whether normal braking is still intact. Some cars will still have standard braking with ABS disabled. Others may have a real hydraulic problem behind the warnings.

Okay to Keep Driving for Now

Only if the pedal feels firm, the car stops normally, the fluid level is not dropping, and the warning appears to be limited to ABS operation. Even then, drive cautiously and fix it soon because ABS and stability features may be unavailable.

Maybe Okay for a Very Short Distance

A very short drive to a nearby shop may be reasonable if braking feels mostly normal but you have low fluid from pad wear or an intermittent sensor fault. Avoid highway speeds, heavy traffic, towing, or bad weather until the cause is confirmed.

Not Safe to Keep Driving

Do not keep driving if the pedal is soft or sinking, the car pulls hard, braking distance is clearly worse, you see fluid leaking, or the red brake warning light is on with obvious braking problems. Those signs point to a base brake system problem, not just a lost ABS function.

How to Fix It

The right fix depends on whether the warning is coming from fluid level, a wheel speed signal problem, an electrical fault, or the hydraulic control side of the ABS system. Good diagnosis matters because several very different problems can turn on the same two lights.

DIY-friendly Checks

Check brake fluid level, inspect for obvious leaks, look at brake pad thickness through the wheel if visible, and inspect exposed ABS sensor wiring for damage or unplugged connectors.

Common Shop Fixes

Typical shop repairs include replacing a wheel speed sensor, repairing a damaged harness, replacing worn brake pads that caused low fluid, fixing a leaking caliper or hose, or replacing a damaged hub or tone ring.

Higher-skill Repairs

More advanced repairs include master cylinder replacement, ABS hydraulic control unit replacement or programming, pressure bleeding, and scan-tool guided ABS bleed procedures after hydraulic repairs.

Related Repair Guides

Typical Repair Costs

Repair cost depends on the vehicle, labor rates, and the exact fault that turned the lights on. The ranges below are typical U.S. parts-and-labor estimates, not exact quotes for every make and model.

Brake Fluid Service and Bleed

Typical cost: $90 to $220

This usually applies when the system needs fresh fluid and a proper bleed after minor hydraulic service or contamination concerns.

Wheel Speed Sensor Replacement

Typical cost: $150 to $350

Most cases land here when one sensor or its short harness has failed without needing a hub assembly.

Hub Assembly Replacement with Integrated ABS Encoder

Typical cost: $250 to $650 per wheel

Cost rises when the wheel bearing, hub, or built-in encoder ring is the actual source of the ABS warning.

Brake Hose, Caliper, or Line Leak Repair

Typical cost: $180 to $700

The low end covers a single hose or simple leak, while line routing or caliper replacement pushes the price higher.

Master Cylinder Replacement

Typical cost: $300 to $800

This usually includes parts, labor, and a full brake bleed after replacement.

ABS Control Module or Hydraulic Unit Replacement

Typical cost: $700 to $1,800+

This is one of the more expensive outcomes because parts, programming, and ABS bleed procedures can all add cost.

What Affects Cost?

Whether the fault is a simple sensor issue or a hydraulic repair
Labor access at the affected wheel, line, or ABS unit
OEM versus aftermarket sensor, hub, or module parts
Whether programming or an ABS bleed procedure is required
Rust, seized fittings, or line condition on older vehicles

Cost Takeaway

If the car still brakes normally and the problem traces to one wheel speed sensor, the repair is often in the lower to middle cost range. Costs jump when low fluid is caused by a leak, when a hub assembly is involved, or when the ABS hydraulic unit or master cylinder turns out to be the real problem.

Symptoms That Can Look Similar

Parts and Tools

FAQ

Can Low Brake Fluid Turn on Both the Brake Light and ABS Light?

Yes. Low fluid is one of the most common reasons the red brake warning light comes on, and some vehicles will also disable ABS or set ABS faults when the fluid level drops.

If Both Lights Are On, Do I Still Have Brakes?

Often you still have normal base braking, but ABS may be disabled. That said, you should not assume the brakes are safe if the pedal feels soft, sinks, or the fluid level is low.

Can Worn Brake Pads Cause Both Lights to Come On?

They can indirectly. As pads wear, the caliper pistons sit farther out and the fluid level in the reservoir drops. On some vehicles, that drop is enough to trigger the brake warning and sometimes related ABS warnings.

Why Did the Lights Come on Right After Brake or Hub Work?

A disturbed wheel speed sensor, damaged sensor wiring, improper sensor gap, trapped air, or a missed ABS bleed procedure are all common reasons the warning shows up after service.

Do I Need an ABS Scan Tool, or Is a Basic Code Reader Enough?

A basic engine code reader often cannot read ABS module codes. For this symptom, an ABS-capable scan tool is much more useful because it can identify the affected wheel or module fault instead of forcing you to guess.

Final Thoughts

When the brake and ABS lights come on together, start by separating a light-only ABS problem from a real hydraulic braking problem. Fluid level, pedal feel, and ABS codes usually tell you which direction to go first.

If the pedal feels normal, a wheel speed sensor, tone ring, or wiring issue is common. If the pedal is soft, sinking, or the fluid is low, stop treating it like a simple warning-light issue and address the brake system fault before driving further.