OBD-II Code C0164: Brake Pedal Switch Circuit Malfunction

What Does C0164 Mean?

Code C0164 means the vehicle's computer detected a fault in the brake pedal switch circuit. This switch tells the computer when you press the brake pedal, which is required to activate brake lights, disengage cruise control, enable ABS/traction control, and shift out of Park.

Technical definition: C0164 is defined as 'Brake Pedal Switch Circuit Malfunction'. The control module (EBCM, PCM, or BCM) detects an incorrect voltage, loss of signal, or irrational signal from the brake pedal position switch circuit.

Can I Drive With C0164?

Yes, But With Caution. Yes, but only short distances to a repair shop. Your brake lights may not work, creating a severe rear-end collision risk. Alternatively, they may stay on and drain your battery. A faulty signal also disables ABS and traction control, increasing stopping distances and causing loss of control in emergencies.

Common Causes

• Broken or Missing Brake Pedal Stopper/Bushing (Very Common) — A small plastic or rubber pad on the brake pedal arm presses the switch's plunger. These stoppers become brittle with age, crack, and fall apart. 🎬 Watch this simple tutorial on replacing a broken stopper pad. Without the stopper, the plunger extends fully, causing brake lights to stay on constantly and drain the battery.
• Faulty Brake Pedal Switch (Very Common) — The switch is a mechanical and electrical component activated every time you press the brake pedal. Over thousands of cycles, internal contacts wear out, causing intermittent or total failure.
• Blown Fuse (Common) — A short circuit in the wiring or a faulty component blows the brake light circuit fuse, instantly cutting power to the switch and triggering the code.
• Corroded Ground Connection (Common) — The brake switch circuit requires a clean ground connection. On vehicles like the Ford F-150, a corroded frame ground (e.g., G401) disrupts low-voltage signals, triggering C0164 alongside network communication codes.
• Wiring or Connector Issues (Common) — Wires in the driver's footwell get kicked, stretched, or abraded. Loose connectors or corroded terminals create high resistance or open circuits.
• Aftermarket Modifications (Less Common) — Installing aftermarket LED taillights without proper load resistors, or poorly wiring remote start systems, alters the circuit's expected voltage and triggers the code.
• Improperly Adjusted Switch (Rare) — If recently replaced, the switch might be incorrectly positioned. An improperly adjusted switch activates at the wrong point in the pedal's travel, sending an irrational signal.
• Faulty Control Module (EBCM/BCM/PCM) (Rare) — Rarely, the Electronic Brake Control Module (EBCM) or Body Control Module (BCM) fails internally and misinterprets a perfectly good brake switch signal.

Symptoms

• Brake lights don't work or are stuck on — The brake lights either fail to illuminate when you press the pedal or stay on constantly, even when your foot is off the brake.
• Cannot shift out of Park — The brake-to-shift interlock safety feature locks the shifter in Park because it does not receive the signal that the brake is pressed.
• Car won't start (Push-Button Start models) — Vehicles with push-button start require a brake pedal signal to crank the engine. A faulty switch prevents this, resulting in a no-start condition.
• ABS, Traction Control, or Stability Control warning light is on — These safety systems deactivate and trigger warning lights because they depend on a reliable brake switch signal to function.
• Cruise control does not work or disengages randomly — The cruise control system fails to engage or turns off unexpectedly because it cannot verify the brake pedal status.
• "Service Trailer Brake System" Message (on trucks) — On GM and Ford trucks, a fault in the brake switch triggers a warning message for the integrated trailer brake controller.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this code.

Common Fixes & Costs

• Replace Brake Pedal Stopper/Bushing — Parts: $5-$20, Labor: $0-$60, ~0.5 hr book time (DIY)
• Replace Blown Fuse — Parts: $1-$5, Labor: $0, ~0.1 hr book time (DIY)
• Replace Brake Pedal Switch — Parts: $15-$75, Labor: $90-$180, ~0.8 hr book time (DIY)
• Clean or Repair Frame Ground Connection — Parts: $5, Labor: $75-$150, ~0.8 hr book time (DIY)
• Repair Damaged Wiring or Connector — Parts: $10-$50, Labor: $120-$300, ~1.5 hr book time (Professional)

Used vs. New Parts: Buying Guide

When a used part is worth it: For a brake light switch or stopper pad, buying used never makes sense. These are high-wear, safety-critical parts that cost under $30 brand new.

Donor-vehicle mileage cap: roughly under 10000 miles for the part to have meaningful remaining life.

Donor quality checklist:

• For a simple mechanical switch, there are no reliable quality cues for a used part. Its remaining lifespan is unknown.
• Always match the part number exactly. Even similar-looking switches can have different internal circuits.

Decision logic:

• If The new part (switch or stopper) costs less than $75. → Always buy new. The cost savings from a used part are negligible and not worth the safety risk or the potential cost of repeat labor.
• If The vehicle is very old and an OEM new part is unavailable. → A new aftermarket part is the best choice. A used part should only be considered as an absolute last resort if no new options exist.

Warranty tradeoff: Used parts from a salvage yard typically have a 30-day warranty at best. New aftermarket parts often carry a 1-year to limited lifetime warranty. An OEM part provides the best guarantee of fit and function.

Worst-case if a used part fails: $150-$300. If a used switch fails shortly after installation, you will have to pay for the labor charge a second time, completely erasing any initial savings.

What Happens If You Wait — Timeline

1. Immediate (Day 0): Code C0164 sets. ABS and traction control disable. Brake lights either stick on or fail entirely. (Added cost: $0)
2. 0-2 Days: Stuck lights drain the battery, requiring a jump start or tow. Failed lights risk a traffic citation or rear-end collision. (Added cost: $75 - $2000+)
3. 1-4 Weeks: Driving without ABS increases accident risk. Stuck lights overheat and melt plastic bulb sockets. (Added cost: $20 - $100)
4. 1+ Month: Ignoring underlying electrical shorts or corroded grounds causes cascading module failures, requiring expensive replacements. (Added cost: $1000 - $2500)

Cost of Not Fixing It

• Immediate: Brake lights fail, creating a severe rear-end collision risk. ABS and Traction Control disable, reducing emergency vehicle control. (Added cost: $500+ (Insurance deductible from accident), $100+ (Traffic citation))
• 0-1 Day: Stuck-on brake lights drain the battery overnight, causing a no-start. The shift interlock prevents moving the vehicle out of Park. (Added cost: $75-$200 (Towing fee or roadside assistance))
• 1+ week: Driving without ABS causes flat-spotting on tires during panic stops. Chronically stuck lights melt bulb sockets and prematurely burn out bulbs. (Added cost: $20-$100 (Bulb/socket replacement), $150+ (Tire replacement))

Diagnosis Steps

1. Visually Inspect the Brake Lights and Pedal Area
   Have a helper watch the brake lights as you press the pedal. Note if they are inoperative, always on, or delayed. Look under the dashboard at the brake pedal arm and check the floor mat for broken plastic pieces. A missing stopper pad is the most common cause for stuck-on brake lights.
   Tools: A friend, Flashlight (Beginner)
2. Scan for All Codes
   Use an OBD-II scanner capable of reading Chassis (C-codes) and Network (U-codes) to confirm C0164. Note all other codes. Codes like P0504 or U-codes help differentiate between a simple switch failure and a complex network problem.
   Tools: OBD-II Scanner (C-code capable) (Beginner)
3. Check the Relevant Fuses
   Locate the fuse box and inspect fuses labeled 'STOP', 'BRAKE', or ABS/BCM. A blown fuse is a simple fix but indicates an underlying short circuit that requires further investigation.
   Tools: Owner's manual, Fuse puller or needle-nose pliers (Beginner)
4. Test the Brake Switch Functionality
   With the switch unplugged, set a multimeter to continuity. Connect leads to the switch terminals and press the plunger. The multimeter must beep in one position and stop in the other. Test both sets of terminals for dual-circuit switches.
   Tools: Multimeter (Intermediate)
5. [PRO TIP] Check for Power and Ground at the Switch Connector
   Disconnect the brake switch connector and turn the ignition ON. Use a multimeter set to DC Volts to test the connector terminals. One wire must have constant battery voltage (12.4-12.6V). Switch to Ohms and test the ground wire against a bare metal chassis point; it must read under 1.0 Ohm.
   Tools: Multimeter (Intermediate)
6. [PRO TIP] View Live Data with an Advanced Scan Tool
   Use an advanced scan tool to view the 'Brake Pedal Position' live data PID. The data must toggle between 'On/Off' as you press the pedal. If live data doesn't change but the switch tests good, suspect a wiring issue or faulty module.
   Tools: Advanced OBD-II Scan Tool with Live Data (Advanced)
7. Perform a Voltage Drop Test
   Connect the red multimeter lead to the battery positive and back-probe the black lead to the power wire at the switch connector. A reading above 0.5V indicates excessive resistance. Repeat for the ground side; a reading above 0.2V confirms a poor ground connection.
   Tools: Multimeter with back-probe pins (Advanced)
8. Inspect CAN Bus Network (If U-Codes are Present)
   If U-codes accompany C0164, disconnect the battery and measure resistance between pins 6 and 14 on the OBD-II port. A healthy CAN bus reads 60 Ohms. A 120 Ohm or OL reading indicates a broken circuit or missing terminating resistor, often due to a corroded ground.
   Tools: Multimeter, Vehicle-specific wiring diagrams (Advanced)

When This Code Triggers (Freeze-Frame Conditions)

• Vehicle Speed: 45-65 mph (The code sets when the computer sees a conflict between the brake signal and other data, such as when cruise control is engaged at highway speeds and the brake signal is irrational.)
• Brake Pedal Status: Off/Released (A fault logs when the pedal is released but the switch incorrectly reports it as pressed (or vice-versa), especially when compared against other sensors.)
• RPM: 1500-2500 (Typical engine speed during steady state cruising when cruise control is active and reliant on a valid brake switch signal to disengage.)
• System Voltage: 13.5-14.5V (The fault is typically logged when the engine is running and the charging system is at normal operating voltage.)

Related Codes

• P0504 — Stands for 'Brake Switch A/B Correlation'. Triggers when the dual-circuit switch signals conflict. Seeing C0164 and P0504 together guarantees the brake pedal switch has failed internally.
• P0571 — Means 'Brake Switch A Circuit Malfunction'. This Powertrain code (P-code) often appears alongside C0164 (Chassis code) because the fault affects cruise control. Both codes point to the exact same physical circuit fault.
• U0121 — Means 'Lost Communication With Anti-Lock Brake System Control Module'. Appearing with C0164, this suggests a broken CAN bus network or a failing ABS module, requiring advanced electrical diagnostics.
• C0040 — Points specifically to the 'Brake Pedal Switch A' circuit. It directly implicates the brake pedal switch or immediate wiring, serving as redundant confirmation of the C0164 fault area.

Climate & Environmental Factors

• High Heat: Prolonged exposure to high ambient temperatures accelerates the aging of plastic and rubber components. This causes the brake pedal stopper pad to become brittle, crack, and disintegrate.
• Humidity and Road Salt: Moisture and road salt penetrate wiring connectors and ground points, causing corrosion. This creates high resistance or open circuits, frequently triggering C0164 on frame grounds and exposed harnesses.

How to Talk to a Mechanic About This Code

Say this: "I have an ABS light on and a C0164 code. My brake lights are acting up. Please perform a diagnostic that includes checking the brake pedal stopper, the fuse, and testing power/ground at the switch connector."

This signals to the mechanic that you're an informed customer. It directs them to check the simple, inexpensive, and common failure points first, preventing them from jumping to a costly and potentially unnecessary brake switch or module replacement.

Avoid saying:

• 'My ABS light is on, can you just fix it?'
• 'I think I need a new brake switch.' (Don't diagnose for them)
• 'Just do whatever it takes to get the light off.'

Questions to ask before authorizing the repair:

• Did you find the root cause? Was it the switch, the stopper, the fuse, or the wiring?
• Can you show me the failed part or the test results (e.g., multimeter reading)?
• If you're recommending a module replacement, what specific tests did you perform to rule out everything else?
• What is the warranty on the recommended parts and your labor?

Where to Take It: Dealer vs Independent vs Chain

• Dealer: Recommended only for vehicles under warranty or complex network diagnostics requiring proprietary manufacturer software.
  Best for: Vehicles under warranty, Known manufacturer-specific issues covered by a Technical Service Bulletin (TSB), Complex network diagnostics requiring proprietary manufacturer software
  Downsides: Highest labor rates, often 1.5-2x more than independent shops., May default to replacing a module when a simpler wiring or ground fix is possible. (Typical cost: +50% vs. baseline)
• Independent Shop: Best fit for most C0164 scenarios. An experienced mechanic efficiently handles switches, stoppers, and basic wiring faults.
  Best for: Out-of-warranty vehicles where cost is a factor., Diagnosing and fixing the most common causes of C0164 (stopper, switch, fuse, wiring)., Building a relationship with a trusted mechanic.
  Downsides: Quality and diagnostic capability vary greatly. Look for ASE certifications and good reviews., May not have the latest manufacturer-specific software for module programming. (Typical cost: +0% vs. baseline)
• Chain Shop: Acceptable only for a simple fuse or stopper replacement you have already diagnosed yourself. Avoid for electrical diagnostics.
  Best for: Simple, clear-cut parts replacement like a blown fuse or a visually confirmed broken pedal stopper.
  Downsides: High pressure to upsell; may recommend a new switch when only a stopper is needed., Technician skill varies dramatically; may lack the experience for electrical or network diagnostics., Often not equipped or trained to handle complex wiring or module-level problems. (Typical cost: -10% vs. baseline)

When to Walk Away From the Repair

If the estimated repair cost for the C0164 fault exceeds 40-50% of your car's private-party value, pause and evaluate your options. A high estimate often warrants a second opinion before making a decision.

• Car worth $5000, fix is $200: Fix it. This is a routine repair cost well below the threshold.
• Car worth $3000, fix is $1200: Get a second opinion. A $1200 quote likely means the shop is recommending an expensive module replacement. The actual cause could be much cheaper, like a corroded ground wire.
• Car worth $2000, fix is $1500: Walk away. If a second opinion confirms a major failure (like a faulty ABS module) and the cost is this high relative to the car's value, consider selling or scrapping the vehicle.

What Scan Tool You Need for This Code

Minimum: A scanner that reads and clears Chassis (C-codes) for the ABS system. It must also display live data for the brake switch status.

A basic $20 'check engine light' reader only scans for Powertrain (P-codes). It will not see the C0164 code, which is stored in the ABS or Body Control Module.

Budget: Innova 5210 / BlueDriver Pro (~$99) — Reads ABS codes and displays live data for brake pedal position.

Mid-range: Foxwell NT510 Elite / Autel AL619 (~$150) — Adds manufacturer-specific data and automated ABS bleeding functions.

Professional: Autel MaxiCOM MK808S (~$450) — Offers full bidirectional control to command components and run active tests without replacing parts.

How to Clear the Code After You Fix It

1. Use an OBD-II scan tool to clear the C0164 and any related fault codes.
2. Perform a function test: with the ignition on, confirm brake lights operate correctly and that the vehicle can shift out of Park.
3. Perform a complete drive cycle to allow the vehicle's readiness monitors to run.

Drive cycle (~30 minutes): After a cold start (sit for 8+ hours), idle for 2-3 minutes. Drive a mix of city (stop-and-go) and highway speeds. Maintain a steady speed of around 55 mph for 5-10 minutes. Allow the vehicle to cool down.

Readiness monitors affected: Comprehensive Component Monitor, EGR System, Oxygen Sensor

Before emissions retest: drive at least 50 miles to fully set monitors.

Watch out for:

• Simply disconnecting the battery clears the code but resets all readiness monitors, causing an immediate emissions test failure.
• The code returns immediately if the underlying mechanical or electrical fault is not properly fixed.

Will This Fail Emissions / State Inspection?

Yes — this code typically fails an OBD-II emissions inspection.

• California: An active C0164 code or illuminated ABS light causes an automatic smog check failure during the OBD-II system inspection.
• New York: Inoperative brake lights result in an immediate safety inspection failure. The active code also fails the emissions scan.
• Texas: The annual safety inspection requires fully operational brake lights. A faulty switch causing light failure guarantees an immediate rejection.

Most Commonly Affected Vehicles

• Chevrolet/GMC Silverado/Sierra 1500/2500HD (2013-2019) — Often presents with a "Service Trailer Brake System" message. The cause is frequently corrosion in the wiring harness near the spare tire or a software error in the Electronic Brake Control Module (EBCM).
• Hyundai/Kia Elantra, Sonata, Forte, Optima, Sorento (2006-2019) — Subject to massive recalls for faulty ABS modules that leak fluid internally, causing electrical shorts. Other major recalls target both faulty brake switches and deteriorating brake pedal stopper pads.
• Honda CR-V, Pilot, Ridgeline (2016-2019) — These models experience phantom braking from the collision mitigation system and battery drain issues related to brake circuit monitoring.
• Nissan Murano, Pathfinder, Maxima (2015-2019) — Subject to a major recall where ABS actuator pumps leak brake fluid onto the internal circuit board, causing an electrical short and fire risk.
• Toyota Tacoma (2016-2021) — Commonly triggered by installing aftermarket LED tail lights without correct load resistors. The vehicle's computer detects the lower power draw as a fault.
• Ford F-150 (2015-2020) — C0164 often appears with a host of U-codes. The root cause is frequently a corroded MS-CAN bus ground connection (G401) on the frame rail under the driver's door.
• Toyota Camry/Corolla (2012-2019) — The code is most often due to simple failure of the brake light switch from high mileage and normal wear. It is a very common and straightforward DIY replacement.
• Ford Police Interceptor Utility (Explorer) (2013-2019) — These vehicles experience extreme use, leading to accelerated wear of all components, making the brake pedal switch a common failure point.

Manufacturer-Specific Notes

• General Motors (Chevy/GMC): On trucks, C0164 frequently links to corroded wiring for the trailer brake control module above the spare tire. A 2019 software glitch in the EBCM also caused this code, prompting recall N192268090.
• Toyota: The brake override system is highly sensitive. Installing aftermarket LED tail lights without load resistors causes the computer to misinterpret the low power draw as a circuit fault, triggering C0164.
• Ford: On 2015-2020 F-150s, C0164 paired with multiple U-codes is a classic symptom of a corroded MS-CAN bus ground (G401) on the frame under the driver's door. Clean this ground before replacing modules.
• Hyundai/Kia: Massive recalls exist for deteriorating brake pedal stoppers and faulty brake light switches across millions of vehicles. Always check your VIN for open recalls before paying for repairs.

Real Owner Stories

2013 Hyundai Elantra at 75K miles

Owner discovered brake lights were staying on constantly, even with the car off, leading to a dead battery.

What they tried:

1. Initially suspected a bad brake light switch.
2. Searched online forums and found information about a common failure.
3. Inspected the driver's footwell and found small, broken blue plastic pieces on the floor mat.

Outcome: The brake pedal stopper pad had disintegrated. The owner purchased a replacement part (Dorman 74015) for under $10. The new stopper snapped into the brake pedal arm, immediately fixing the problem.

Lesson: If your brake lights are stuck on, especially on a Hyundai/Kia, check for broken plastic bits on your floor mat before buying electrical parts. This is a common, inexpensive DIY fix.

2016 Ford F-150 at 110K miles

ABS and Traction Control lights came on, cruise control stopped working, and the scanner showed code C0164 along with multiple U-codes.

What they tried:

1. A mechanic diagnosed a faulty ABS module, quoting over $1,000.
2. Owner researched F-150 forums and found stories pointing to a specific ground point.
3. Inspected the frame rail under the driver's side door and located the G401 ground connection, which was visibly corroded.

Outcome: The owner disconnected the battery, cleaned the contact surfaces on the frame and the wire terminal with a wire brush, and re-secured the connection. All codes cleared and systems functioned normally. Total cost was under $5.

Lesson: On modern trucks, a cluster of communication U-codes alongside C0164 points to a network-wide problem. Always check common corrosion points, like major frame grounds, before replacing expensive modules.

2017 Toyota Tacoma at 50K miles

Check engine light and ABS light appeared shortly after installing new aftermarket LED taillight assemblies.

What they tried:

1. Scanned the vehicle and found code C0164.
2. Replaced the brake pedal switch, but the code returned immediately.
3. Tested the new switch and wiring, which showed no faults.

Outcome: The owner learned the Body Control Module (BCM) is sensitive to the electrical resistance of the brake light circuit. The low power draw of the LEDs was interpreted as a circuit fault. Wiring a 6-ohm, 50-watt load resistor in parallel with each taillight resolved the issue.

Lesson: If a fault code appears immediately after installing aftermarket lighting, the new part is the likely cause. Many modern cars require load resistors to make LED lights compatible with the factory computer.

How to Prevent This Code From Triggering

• Apply dielectric grease to electrical connectors (When replacing a switch or bulb, or every 2-3 years in harsh climates) — Apply dielectric grease to connector pins and ground points to repel moisture and prevent corrosion, especially in harsh climates.
• Periodically inspect and clean major ground points (Every 30,000 miles or during underbody service) — Clean key frame ground connections every 30,000 miles to prevent high resistance that disrupts module communication.
• Avoid splicing wires when installing accessories (During any aftermarket installation) — Use plug-and-play harnesses instead of cutting factory wiring to prevent moisture entry and corrosion.
• Check for open recalls on your vehicle (Annually) — Check the NHTSA website annually with your VIN to catch free manufacturer fixes for known brake switch or stopper defects.

Frequently Asked Questions

I replaced the brake switch, but the C0164 code came back. What now?

If a new switch doesn't fix it, check for a broken plastic stopper pad on the pedal arm or a blown fuse. Next, use a multimeter to verify 12V power and a solid ground (less than 1.0 Ohm) at the switch connector. Finally, if U-codes are present, the issue is likely a network communication problem, not the switch.

What is the most common misdiagnosis for a C0164 code?

The most common misdiagnosis is replacing the brake pedal switch without performing basic electrical tests. Technicians often overlook a blown fuse, a broken pedal stopper pad, or a poor ground connection. Ignoring accompanying U-codes is another pitfall, as they point to a network issue rather than a faulty switch.

Is it safe to drive with code C0164?

No, driving with C0164 is highly dangerous. Your brake lights may fail, creating a severe rear-end collision risk. Critical safety systems like ABS and traction control are also disabled, significantly reducing vehicle control in emergencies.

Why are my brake lights stuck on?

Stuck brake lights are most often caused by a shattered plastic or rubber stopper pad on the brake pedal arm. Without this stopper, the switch's plunger over-extends when the pedal is released, keeping the circuit permanently active. You will often find the broken plastic pieces on your floor mat.

Can I fix code C0164 myself?

Yes, the most common causes—a broken stopper pad, a blown fuse, or a faulty switch—are inexpensive and accessible with basic hand tools. Replacing a stopper or fuse takes minutes and requires no special skills. Replacing the switch itself is slightly more involved but remains a popular DIY repair.

How much does it cost to fix C0164?

A professional brake light switch replacement typically costs $120 to $200, including parts and labor. Fixing a broken stopper pad is much cheaper, often under $20 for the part and 30 minutes of labor. Diagnostic fees from a dealership or shop usually add $120 to $180 to the total bill.

Will a bad brake light switch drain my battery?

Yes. If the switch or pedal stopper fails in a way that keeps the brake lights permanently illuminated, it will drain your vehicle's battery. This often results in a dead battery overnight.

What is a brake pedal stopper and where is it?

The stopper is a small plastic or rubber pad located on the brake pedal arm under the dashboard. It physically presses against the brake light switch plunger when you release the pedal to turn the lights off. When it breaks, the plunger extends fully, keeping the brake lights permanently on.

Key Takeaways

• Code C0164 disables critical safety systems like ABS and traction control, while also preventing you from shifting out of Park or starting push-button vehicles.
• Check your driver-side floor mat for broken plastic pieces; a shattered $10 brake pedal stopper pad is the most common cause of brake lights staying stuck on.
• Test the brake switch circuit with a multimeter before replacing parts; a blown $2 fuse or a corroded ground wire frequently triggers this code.
• Do not drive with an active C0164 code, as inoperative brake lights create a severe rear-end collision risk and can result in a $100+ traffic citation.