ABS Sensor: Wheel Speed Sensor Symptoms, Location, Tests

When the ABS sensor at one wheel stops reporting, your car switches off anti-lock braking and turns off traction and stability control with it. That's why a part smaller than your thumb can light two or three warnings at once.

What catches people out is that the carmaker's fix isn't always a new sensor. For one common fault, GM tells its dealers most repairs need no new sensor at all: just metal debris wiped off a magnetic ring behind the wheel, never with a magnet.

Below are the symptoms, how a shop finds which of the four sensors is at fault, where each one sits, and the tests that prove it before you buy a part. The sensor is cheap; buying the wrong one twice is the expensive part.

What is an ABS sensor?

An ABS sensor is a small magnetic sensor at a wheel that counts how fast the wheel turns and sends that count to the anti-lock brake module. Traction and stability control read the same count, which is why one failed sensor can switch all three off.

It reads a ring that turns with the wheel: on many cars, a toothed steel ring. Newer ones can read a magnetic ring in the wheel bearing's seal, which GM describes as magnetized rubber, typically brown.

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Sensors come in two kinds, and the difference matters when you test one. A passive sensor is a magnet inside a coil of wire that makes its own small AC voltage as the teeth pass: the faster the wheel, the stronger the signal.

An active sensor takes power from the ABS module and sends a switching signal that works almost down to a standstill, say Hella and Bosch, two sensor makers. Hella adds that the two kinds can look alike, so a test starts with knowing which one your car has.

What the documents say 4 documents

• Federal rule FMVSS 126, stability controlDefines stability control as a system that can brake individual wheels; the wheel speed sensors feed it.
• GM, bulletin 17-NA-047, February 2017Describes the encoder as "a magnetized nitrile rubber ring, typically brown in color", on the inboard side of the bearing hub.
• Hella, sensor maker's guideA sensor that needs supply voltage is active, one that works without is passive; active sensors read a multipole magnet ring, which can sit in a wheel-bearing seal, or a steel wheel with a magnet in the sensor.
• Bosch, sensor makerActive sensors detect wheel speed "nearly up to stand-still (0.1 km/h)".

What are the symptoms of a bad wheel speed sensor?

The first symptom is the ABS light, and on cars with traction and stability control their warning comes on with it, because all three lose the same wheel-speed signal. The other signs depend on how the sensor is failing: some set no code at all, and some come and go with the weather.

Here are the six signs carmakers' documents tie to a failing wheel speed sensor, starting with the one you'll see first:

1. The ABS light, with traction or stability

When the ABS module stops getting a believable speed from one wheel, it stores a fault code for that wheel, lights the ABS warning and switches off anti-lock braking. Traction and stability control rely on the same signal, so their light comes on too, and on GM's cars a message such as "Service StabiliTrak" joins it.

A steady light with a stored code is the easy case, because the code already names the corner. The tests section below shows how a shop reads it.

ABS and traction lights 2 documents

• GM, bulletin 17-NA-047, 2007 to 2017 models including the Equinox, Traverse and CruzeABS, Service Traction Control and/or Service StabiliTrak lights with codes C0035 to C0050, one code per wheel.
• GM, program 18308, 2018 Malibu"If the sensor fails, the telltale light for anti-lock brakes (ABS) and/or traction control – electronic stability control will illuminate, and those functions will be disabled for the duration of the ignition cycle."

2. Clicking or a pulsing pedal at low speed

A sensor that reads a wheel as slowing when it isn't makes the ABS think that wheel is about to lock. The system then pulses the brake at a parking-lot crawl, which you hear as a click, a ratchet or the ABS pump, and feel as a buzz in the pedal.

GM notes this can happen with no code stored, so the light may never come on, and it points at the magnetic ring rather than the sensor. Brake noises that aren't the ABS are on our page on a knocking noise when braking.

ABS acting at low speed 3 documents

• GM, bulletin 17-NA-047"A brief and intermittent noise, click, ratchet, grind, or ABS pump motor noises typically heard from the inside of the vehicle at parking lot speeds", and "A flashing Traction Control or Stabilitrak telltale at low speeds", both with no code set.
• Kia, campaign SC301, 2020 to 2024 TellurideMoisture corrosion can make the sensor signal fluctuate, "in rare cases" causing momentary ABS activation at low speed while braking.
• GM, recall 04V190, 2004 MalibuAn erratic rear wheel speed signal could trigger unneeded ABS activation, with stops up to about 11 feet longer.

3. Lights that come and go

Water in a sensor's housing or a cracked wire can break the signal only some of the time. The light comes on in rain or after a car wash and goes out once the sensor dries, or it flickers on as the suspension moves in a turn.

A fault that shows up only in the rain rarely performs on cue at the shop, so write down when it happens: after rain, on turns, over bumps. The ABS module may still hold the code, and your note tells the shop whether to look at the sensor or its wire.

Lights that come and go 3 documents

• Hyundai, campaign 949, Santa Fe and Santa Fe Sport built 2012 to 2016Salt water can enter the rear sensor housing and "temporarily illuminate the ABS and/or ESC warning lights" until the sensor dries.
• GM, bulletin PIC5992, 2007 to 2013 Impala and othersABS and/or traction light "more easily duplicated while turning", from a broken wire inside the front sensor harness insulation.
• GM, bulletin 17-NA-223, 2017 Equinox and TerrainABS and/or StabiliTrak light from "water intrusion into the left and/or right side wheel speed sensor".

4. Other warning messages

Every system that uses wheel speed can complain at once: brake assist and all-wheel drive on the cars that have them. It looks like several faults, but it's one missing signal, reported by every system that was listening.

Treat several warning lights that arrived together as one fault until the codes say otherwise. A shop that reads the ABS codes first saves you from chasing each message separately.

Messages from one sensor 2 documents

• GM, bulletin 16-NA-090, 2016 to 2017 VoltABS and StabiliTrak lights with "Service Brake Assist" and "Service StabiliTrak" from a mis-routed or twisted front sensor harness.
• GM, bulletin 16-NA-248, 2016 Buick EnvisionStabiliTrak, traction and all-wheel-drive disabled messages from "an internally shorted front wheel speed sensor".

5. Heavier steering at low speed

On cars with electric power steering, the steering computer uses vehicle speed to decide how much to help. If that speed goes missing, some cars show a steering message and give less help at low speed, which feels like a heavy wheel in a parking lot.

That isn't a failing steering rack. GM calls it a normal default action when a wheel speed signal is lost, and the ABS code points back to the sensor.

Steering assist 1 document

• GM, bulletin 17-NA-047On cars with electric power steering, a lost wheel speed signal also brings a Service Steering message and heavier steering at low speed, "a normal default action".

6. What doesn't change: your normal brakes

A bad ABS sensor doesn't take away your ordinary braking. The pedal, the pads and the stopping power are the same; what's gone is anti-lock and stability control in a panic stop or on a slippery road.

The federal rule behind that, and when a second light means stop, is on our ABS light page.

Braking with the fault 1 document

• Kia, campaign SC301, 2020 to 2024 TellurideOn the sensor fault it fixes: "The ability to stop the vehicle is unaffected by this issue."

How do you tell which ABS sensor is bad?

A scan tool that reads ABS codes tells you, because each wheel's sensor has its own code. Ask for an ABS scan specifically: these are chassis codes, starting with a C, stored in the ABS module rather than the engine computer.

A code names a circuit, though, not a part. So the test for a bad wheel speed sensor runs in the 5 steps below, in the order carmakers and sensor makers give, before anyone buys a sensor:

1. Read the ABS code and note the wheel. On GM's cars, for example, C0035 is the left front, C0040 the right front, C0045 the left rear and C0050 the right rear.
2. Compare the four wheel speeds while driving. A scan tool shows each sensor's reading live, and Delphi, a sensor maker, lists live data among its checks: the bad one disagrees with the other three or drops out. If all four read normally, the lights have another cause, and our ABS light page covers those.
3. Check the wire and connector along the whole run. FCA told Wrangler technicians to check the wiring and connection before replacing a sensor, and GM warns a wire broken inside its insulation can still pass a resistance check.
4. Test the sensor itself, by its type. A passive sensor can be checked with a multimeter; an active one needs its supply voltage and signal checked instead. The two methods are below.
5. Look at the ring and the bearing. Debris on a magnetic ring, a dented ring or a loose bearing makes a good sensor read badly, and a new sensor won't fix it.

How to test a wheel speed sensor with a multimeter

A multimeter works on a passive sensor, the two-terminal kind with a coil inside. Unplugged, its resistance across the terminals should match the carmaker's figure; Standard Motor Products, a parts maker, says it's typically somewhere between 1,000 and 2,500 ohms.

Spinning the wheel by hand should then show a small AC voltage that rises with speed. Because the signal depends on speed, SMP notes these sensors aren't considered effective at low speeds.

How to test an active wheel speed sensor

A resistance reading tells you nothing here: Hella says the internal resistance of an active sensor can't be measured. The check is whether the ABS module is feeding it power and whether it sends back a clean switching signal as the wheel turns.

GM gives its own numbers for its cars, a signal that switches between 7 and 14 milliamps, and an oscilloscope shows it best. If you're not set up for that, this is a test to ask a shop for by name.

After the repair: clear the code and drive

Hella's procedure ends by clearing the stored codes and test-driving with the scan tool connected. On that drive, the repaired wheel's speed should match the other three.

If the code comes back, the fault was somewhere else in the circuit. That's the moment to go back to the wire and the ring, not to buy a second sensor.

Don't swap sensors to find the bad one

Moving a sensor from one side to the other to see whether the fault follows sounds like a free test. VW told its dealers to stop: the swapping ground down the magnetic ring on the bearing, turning one fault into two.

The same goes for buying a sensor on a hunch. GM found technicians fitting the wrong front sensor on its pickups, and then replacing ABS modules and bearings chasing the fault it caused.

Tests and traps 6 documents

• GM, bulletin 17-NA-047Codes C0035, C0040, C0045 and C0050 name the four wheels; the active sensor signal switches "between 7mA (Low) and 14mA (High) DC current".
• FCA, tech tip 52125003A$, 2015 to 2016 Jeep Wrangler"Before replacing the wheel speed sensors, please check for wiring/connection to the speed sensor."
• GM, bulletin PIC5992, 2007 to 2013 Impala and others"Ohm checking the WSS jumper harness may not identify a concern."
• VW, tech tip TT 44-14-02, 2012 to 2015 Passat, Jetta, Beetle, Golf and TiguanEncoder ring ground down by "swapping the speed sensors left to right (or vice versa) during diagnosis".
• GM, bulletin PIT5950B, 2019 to 2025 Silverado and Sierra 1500The front sensors "look very similar and there have been many cases where the wrong sensor has been installed", followed by unnecessary modules, bearings and sensors.
• Standard Motor Products and Hella, parts makers' guidesPassive sensors typically 1,000 to 2,500 ohms (SMP); the resistance of an active sensor can't be measured (Hella).

Where is the ABS sensor located?

Most cars have one at each wheel, four in all, and the ABS code tells you which corner to look at. Here's where the ABS sensor is located at each wheel, front first:

Front wheels: in the knuckle, behind the rotor

At the front it's held in the steering knuckle or hub carrier just behind the brake rotor, with its tip facing the ring that turns with the wheel. From the front of the car you can't see it; with the wheel off, you follow its wire back to where it enters the knuckle.

That wire runs along the suspension, held by clips, to a connector and on to the ABS module. Many of the faults in this article happen along that short run or at the ring, not inside the sensor.

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Rear wheels: in the knuckle, or inside the hub

At the rear it sits the same way on many cars, but on some the rear sensor is sold only as part of the wheel hub, so replacing it means replacing the hub.

It's worth asking. Hyundai's bulletin for its front-wheel-drive Santa Fe and Veracruz says the rear sensor is available on its own, so we'd check the parts listing before accepting a quote for a whole hub.

Left and right: lookalike parts

Left and right sensors can also look almost identical while being different parts.

Check the part number for the exact corner, because the wrong one can fit and still read wrong. GM found exactly that on its newer full-size pickups, as the causes below explain.

Where the sensors sit 4 sources

• GM, bulletin 17-NA-047The magnetic encoder is on the inboard side of the bearing hub, where the sensor reads it.
• GM, program 18308, 2018 MalibuThe right knuckle's sensor hole was machined "approximately 1.6mm off location", placing the sensor too far from the bearing.
• Hyundai, bulletin 19-BR-001H, front-wheel-drive Santa Fe and others from 2007"The rear wheel speed sensor is available as a separate service part from the rear wheel hub assembly."
• RockAuto catalog, 2018 Toyota Camry 2.5LFront sensors listed on their own; no rear sensor listed separately, read September 29, 2026.

What makes an ABS sensor fail?

Often its surroundings: carmakers' bulletins name dirt, water, salt, damaged wiring and worn bearings, each of which can make a good sensor read badly. Here are the six causes carmakers' bulletins and recalls name, each with what to check before paying for a part:

1. Metal debris on the magnetic ring

A magnetic encoder ring attracts fine steel particles, and a crust of them blurs the north and south poles the sensor counts. The signal turns erratic, and the ABS reacts to a wheel that isn't really slipping.

GM and Stellantis both treat this as a cleaning job first. Ask the shop to inspect and clean the ring before quoting a sensor or a bearing; how they're allowed to clean it is in the cleaning section below.

Debris on the ring 2 documents

• GM, bulletin 17-NA-047, 2007 to 2017 Acadia, Enclave, Equinox, Terrain, Traverse, Cruze, Impala and othersCause: "ferrous metallic debris stuck to the wheel speed sensor magnetic encoder ring". "Most repairs can be performed without any replacement of the bearing hub assembly or wheel speed sensor."
• Stellantis, bulletin S2523000091, 2019 to 2026 Ram 1500ABS light and an intermittent or implausible wheel speed signal: clean dirt or metal debris off the encoder, or replace the bearing if the encoder is dented or gouged.

2. Water and road salt

Water that gets into a sensor housing or its connector interrupts the signal, and salt corrodes the contacts and the mounting surface. On the cars that have had it, carmakers fixed it with seals, new covers, software or new sensors, free under a campaign.

Run your VIN through our free VIN checker or at nhtsa.gov/recalls before paying. A campaign repair costs you nothing, and some are limited to coastal or salt-belt states.

Water and salt 4 documents

• Kia, campaign SC148, 2011 to 2015 two-wheel-drive Sorento, coastal statesSeawater can enter the rear sensor covers and "interrupt the rear wheel speed sensor signal"; covers inspected, cleaned and sealed.
• Kia, campaigns SC301 and SC301Y, 2020 to 2024 TellurideMoisture corrosion in the sensors; software update, then both rear sensors replaced if a rear code returns.
• Hyundai, campaign 949, Santa Fe and Santa Fe SportSalt water in the rear sensor housing; the cap replaced if the light is on with codes.
• GM, recall 05V379, 1999 to 2002 Silverado, Sierra, Tahoe, Suburban and YukonUnwanted ABS activation in corrosive areas; the fix cleaned the sensor mounting surface, added rust inhibitor and reinstalled the sensor.

3. A damaged wire or clip

The wire flexes every time the suspension moves, so a harness that rubs, twists or loses a clip can break inside its insulation. The sensor is fine, but its signal never reaches the ABS module cleanly.

Ask for the whole run to be inspected, clips included, before a sensor is ordered. Subaru even traced broken clips to the acids in some wheel cleaners, so what you spray on your wheels matters.

Wiring faults 4 documents

• Ford, bulletin 20-2302, 2020 EscapeFront sensor wiring rubbing, fixed with a repair kit.
• GM, bulletin 16-NA-090, 2016 to 2017 Volt"mis-routing or twisting of the front wheel speed sensor wiring harness".
• Subaru, bulletin 06-49-15R, 2010 to 2014 Legacy and Outback"cracked or broken ABS wheel speed sensor harness retaining clips caused by reaction with acids used in some wheel cleaners".
• Subaru, bulletin 06-69-19R, 2015 to 2018 Legacy and OutbackA shielding cover added to the rear sensor "to protect the harness from damage caused by road debris".

4. Work done at the wheel

The sensor and its wire sit right where brake, bearing, tire and suspension work happens. A light that comes on days after that work often has a simple cause: a pinched wire, a sensor knocked or left unplugged, or a ring nicked during the job.

If the light appeared right after a brake job or other work at the wheel, go back to the shop that did it first and ask them to check the sensor and its wire. Delphi lists damage during other brake work among the sensor's common failures.

After other work 2 sources

• Stellantis, bulletin S2408000084, 2024 Jeep WranglerABS lamp "after a recent repair service" with a right front sensor circuit code: "Inspect the right front harness routing for signs of harness pinching".
• Delphi, sensor maker's guideNames "Damage during replacement of other braking components" among the causes of sensor failure.

5. The wrong part, or a part fitted wrong

A sensor has to sit at the right distance from its ring, facing the right way. The wrong side's sensor, a hole machined in the wrong place or a sensor mounted backwards can all leave a new part reading badly from the day it went in.

If a new sensor didn't fix the light, check the part number against the corner before blaming the module. FCA even has a code that means "incorrect component installed".

Wrong or misfitted parts 3 documents

• GM, bulletin PIT5950B, 2019 to 2025 Silverado and Sierra 1500Wrong front sensor fitted; check the part number and that "the flat side of the sensor tip is orientated towards the wheel bearing magnetic encoder ring".
• FCA, technical notes, 2006 to 2015 modelsCodes C0037-4A and C003A-4A mean a rear sensor "incorrect component installed".
• Honda, recall 04V536, 2005 OdysseyRear sensors installed incorrectly at the factory, reporting the wrong wheel speed.

6. A worn bearing or damaged ring

When the ring is part of the wheel bearing, a bearing with play or a dented ring moves the target under the sensor, and the signal wobbles with it. Replacing the sensor changes nothing, because the fault is the thing it reads.

On those cars the repair is the bearing or hub, which costs more, so it's worth confirming the ring is damaged first. The other signs of a worn bearing are in our guide to driving on a bad wheel bearing.

Bearing and ring 2 documents

• Ram, recall 24V794, 2025 Ram 1500"The front wheel hub encoder rings may be damaged, which can disable the electronic stability control system"; front hub bearings inspected and replaced.
• Stellantis, bulletin S2523000091, 2019 to 2026 Ram 1500If the encoder surface is dented or gouged, the bearing is replaced rather than the sensor.

Can you clean an ABS sensor?

Yes, and GM and Stellantis have their technicians clean the ring before replacing parts, but they're strict about how. The magnetic ring is easy to ruin, and the tools most people reach for are the ones they forbid.

From GM's and Stellantis's procedures, what's allowed on the sensor and its magnetic ring is short:

• A dry, soft nylon brushGM's first step, to lift debris off the ring without scratching it.
• Mild soap, then a clean clothGM allows mild soap if the brush isn't enough; Stellantis wipes the ring and sensor head with a microfiber cloth.

And what both carmakers forbid, even though page after page online suggests it:

• MagnetsGM warns an external magnet can damage the encoder, and Stellantis says the same.
• Brake cleaner and solventsStellantis rules out cleaning solvents and brake cleaners on the ring and the sensor head.
• Metal brushes, screwdrivers and close-range airAll on Stellantis's list; a sensor maker's wire brush is for the sensor's mounting hole, not the ring.

The ring is often behind the hub, so this is a shop job on many cars, and GM books 0.4 to 2.1 hours per wheel for it. GM also notes its procedure doesn't apply to capped bearings, where the ring can't be reached.

Cleaning procedures 3 documents

• GM, bulletin 17-NA-047"Gently using a dry nylon soft bristle brush"; "Do not use any type of magnetic tool... an external magnet can damage the encoder"; "THIS INFORMATION IS NOT APPLICABLE TO CAPPED WHEEL BEARINGS." Book time 0.4 to 2.1 hours per wheel, by model.
• Stellantis, bulletin S2523000091, 2019 to 2026 Ram 1500"Do NOT use any cleaning solvents, brake cleaners, high-pressure or close-range air, metal brushes or screwdrivers. Do not use magnets."
• Hella, sensor maker's guideClean the sensor's installation point with a wire brush or sandpaper: the mounting hole, not a magnetic ring.

Is it safe to drive with a bad ABS sensor?

For a short while, yes: your normal brakes still stop the car. What you lose is anti-lock and stability control in a panic stop or on a slippery road, so drive gently and get it read soon.

Two exceptions change that. If the red brake light is on too, read our brake warning light page before driving, and if your car has an open recall for the sensor, get that done first.

How much does an ABS sensor cost?

The part costs $6.50 to $255 at the counter across the 13 cars we priced, front and rear, and the box below gives every listing. Labor depends on how it's mounted, from 0.3 hours in Subaru's book times, the hours a carmaker allows for a job, to about three on a 2012 Impreza.

For a whole job, CarMD's 2026 index puts the average wheel speed sensor repair at $314 in 2025, parts and labor together. At the $120 to $159 an hour that almost half of shops charged in a 2025 survey, each hour of book time adds $120 to $159 to the part.

To see that split for your own area, our free fair price calculator prices the part and the labor separately.

Labor times 4 documents

• Subaru, bulletin 06-69-19R, 2015 to 2018 Legacy and Outback0.3 hours to replace one sensor, 0.2 hours for each additional one.
• Kia, campaign SC301Y, 2020 to 2024 Telluride0.6 hours for both rear sensors.
• GM, bulletin 16-NA-248, 2016 Buick Envision0.9 hours for one front sensor, 0.8 hours more for the second.
• Subaru, bulletin 06-56-16, 2012 Impreza2.7 to 3.0 hours, because the rear sensor and upper arm are replaced as a set.

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Common questions

Asked most often

Is an ABS sensor the same as a speed sensor?

An ABS sensor is a wheel speed sensor, usually one at each wheel. The vehicle or transmission speed sensor is usually a different part in the drivetrain, so a quote for one isn't a quote for the other.

Can I replace an ABS sensor myself?

On many cars it's one bolt and one connector, and Subaru's warranty time for one is 0.3 hours. Read the code and test first, match the part number to the corner, and have the code cleared with a scan tool afterwards.

Does a new ABS sensor need to be programmed?

None of the carmaker documents we read programs a new sensor; the light should stay off once the codes are cleared and the module sees a good signal. Kia's Telluride campaign does update the ABS software, but as the fix for a known fault, not a step for a new part.

How do I reset the ABS light after changing a sensor?

Clear the stored code with a scan tool that reads ABS codes, then drive: the module rechecks the sensors once the car is moving. If the light returns, the fault wasn't the sensor, so test the wire and the ring.

Can you drive without an ABS sensor?

The car still brakes normally, but anti-lock and stability control stay off until the sensor works again. Drive gently and get it fixed soon, especially before wet or icy weather.

Can an ABS sensor be cleaned instead of replaced?

Often, when the fault is debris on the magnetic ring. GM's bulletin says most of its repairs need no new sensor; use a soft nylon brush and mild soap, never a magnet, a wire brush or brake cleaner.

Prices are ranges compiled in September 2026 for the US market and vary by region, engine and shop rate. Prices from $10 up are rounded to the nearest dollar, so $14.13 reads as $14 and $14.52 as $15. Below $10 they're exact. This article is general information, not advice about your specific vehicle. See the disclaimer.