OBD-II Code C1252: Brake Booster Pump Motor Running Too Long

What Does C1252 Mean?

Trouble code C1252 means the engine control unit (ECU) detects the brake booster electric motor running for an abnormally long time. This pump creates hydraulic pressure (Toyota/Lexus) or vacuum (Jeep/Ram) for power brakes. Excessive runtime proves the system cannot build or hold pressure, typically due to an internal leak or a failed pump.

Technical definition: The SAE/ISO definition for C1252 is "Brake Booster Pump Motor On Time Abnormally Long". The Skid Control ECU monitors pump operation time. If the motor runs continuously for a set period (typically 90 seconds to 5 minutes) without reaching target pressure, the ECU stores this fault and illuminates critical dashboard warning lights.

Can I Drive With C1252?

No — Do Not Drive. This code indicates a critical failure in the primary power brake system. Continuing to drive results in a sudden, severe loss of braking power with zero warning. Stop the vehicle immediately and tow it to a repair facility.

Common Causes

• Internal Failure of the Brake Booster/Actuator Assembly (Very Common) — The most frequent cause on Toyota and Lexus hybrids. The assembly develops an internal brake fluid leak, preventing the system from holding hydraulic pressure. The pump runs constantly to compensate, triggering the code. Manufacturers acknowledge this widespread failure.
• Failed Electronic Vacuum Pump (Very Common) — On Ford, Ram, and Jeep vehicles, code C1252-92 points to a failed auxiliary electronic vacuum pump. The pump motor shorts internally, blows its dedicated fuse (e.g., F33 on a Ram 1500), and stops creating brake booster vacuum.
• Leaking Vacuum Hoses or Check Valves (Common) — On vehicles with auxiliary vacuum pumps (Jeep/Ram), a cracked or chafed vacuum hose causes a constant loss of vacuum. The pump runs excessively to compensate for the leak, triggering C1252. This leak destroys new pumps prematurely if left unfixed.
• Worn or Failing Brake Booster Pump Motor (Common) — The electric motor wears out from excessive use. Worn internal brushes cause it to run inefficiently or continuously without building pressure. Tapping the motor temporarily restores function, but this does not fix the underlying leak that overworked the motor.
• Failing Brake Accumulator (Less Common) — The accumulator stores hydraulic pressure. If it loses charge due to a ruptured internal diaphragm, the pump works harder and longer to keep the system pressurized, setting code C1252.
• Failing Brake Pump Motor Relay (Less Common) — The relay turns the pump motor on and off. A relay stuck in the 'on' position forces the pump to run continuously. This often triggers a companion code like C1253.
• Improper Brake Bleeding Procedure (Rare) — Performing brake service without the required computer-assisted bleeding procedure traps air in the actuator. Air compresses easily, preventing proper pressure buildup and forcing the pump to run too long.
• PCM Software Anomaly (Rare) — FCA vehicles (Jeep/Ram) have Technical Service Bulletins (e.g., 18-048-22) for Powertrain Control Module (PCM) software updates. The update corrects vacuum pump duty cycle parameters, preventing false C1252-92 codes.
• Failing 12V Auxiliary Battery (Rare) — A weak 12V battery causes unpredictable electronic faults. Low voltage disrupts module communication and sensor data, triggering C1252 as a secondary symptom of the electrical deficit.

Symptoms

• Brake, ABS, and VSC/ESC Warning Lights On — Multiple dashboard warning lights illuminate simultaneously, including the red brake warning light, ABS light, and Vehicle Stability Control (VSC/ESC) light.
• Hard or Stiff Brake Pedal — Power assist fails, making the brake pedal extremely difficult to press. Stopping the vehicle requires massive physical effort. The pedal often feels rock-hard after sitting overnight.
• Loud, Continuous Beeping or Alarm — Toyota and Lexus hybrids sound a persistent, loud cabin alarm to alert the driver to a critical brake system failure.
• Pump Motor Constantly Running or Cycling — A buzzing or whirring noise from the engine bay cycles on and off every 15-30 seconds, even when parked without pressing the brakes.
• Reduced or Inconsistent Braking Performance — Braking feel changes intermittently before total failure. The pedal feels spongy one moment and firm the next, proving the system struggles to maintain pressure.

Diagnostic Flowchart

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

Common Fixes & Costs

• Replace Brake Actuator & Pump Assembly — Parts: $1000-$2000, Labor: $800-$1500, ~6.5 hr book time (Professional)
• Replace Electronic Vacuum Pump — Parts: $250-$500, Labor: $150-$250, ~1.2 hr book time (Intermediate)
• Replace Brake Booster Pump Assembly Only — Parts: $400-$1200, Labor: $400-$800, ~5 hr book time (Professional)
• Perform Computer-Assisted Brake Bleed — Parts: $20-$40, Labor: $150-$250, ~1.5 hr book time (Professional)
• Update PCM Software — Parts: $0, Labor: $100-$200, ~0.8 hr book time (Professional)

Used vs. New Parts: Buying Guide

When a used part is worth it: A used OEM Ram/Jeep electronic vacuum pump from a low-mileage donor is cost-effective. Buying a used Toyota/Lexus brake actuator is extremely risky and never recommended due to internal wear.

Donor-vehicle mileage cap: roughly under 60000 miles for the part to have meaningful remaining life.

Donor quality checklist:

• Inspect vacuum pump plastic housings for cracks and ensure ports are undamaged.
• Verify the OEM part number matches exactly.
• Avoid used Toyota/Lexus brake actuators entirely.

Decision logic:

• If The failed part is a Toyota/Lexus brake actuator assembly → Buy a new OEM part. The savings from a used part never justify the safety risk and guaranteed repeat failure.
• If The failed part is a Ram/Jeep electronic vacuum pump and budget is tight → Buy a used OEM part from a donor with under 60,000 miles. Inspect it carefully.
• If Reliability is the top priority → Always buy a new OEM part.

Warranty tradeoff: Used parts offer 30-90 day warranties. New aftermarket parts offer 1-year warranties. New OEM parts carry manufacturer warranties (e.g., 12 months/12,000 miles).

Worst-case if a used part fails: $500-$1500 in repeated labor costs if a used part fails after installation.

What Happens If You Wait — Timeline

1. First Occurrence - 2 Weeks: Intermittent faults occur. Brake warning lights and alarms appear briefly, especially in cold weather. The pump motor runs slightly longer than usual. (Added cost: $0)
2. 2 Weeks - 2 Months: The pump motor audibly runs every 15-30 seconds to fight the growing leak. Warning lights stay on longer. The brake pedal feels consistently hard or spongy. (Added cost: $50-$200 (Excessive wear on the pump motor and relay).)
3. 2 - 4 Months: The pump motor runs continuously. Internal brushes wear out rapidly. On FCA vehicles, the pump fuse blows. On Toyota vehicles, regenerative braking disables. (Added cost: $400-$800 (The pump motor is destroyed from being overworked).)
4. 4+ Months: Complete failure. The pump motor burns out entirely. Warning lights and alarms are permanent. The brake pedal is rock-hard with zero power assist. (Added cost: $2500-$4700 (Full repair cost of the entire assembly, plus a tow).)

Cost of Not Fixing It

• Immediate (First Occurrence): Intermittent loss of power brake assist. The brake pedal suddenly becomes hard, requiring massive force to stop. The vehicle is unsafe. (Added cost: High risk of collision due to unexpected stopping distance increases.)
• Short-Term (Days to Weeks): The brake booster pump motor overworks continuously to fight the leak. This excessive runtime destroys the motor. (Added cost: $0 (Progression of the primary failure).)
• Medium-Term (Weeks to a Month): Complete power brake system failure. The pump motor burns out, warning lights stay on permanently, and the brake pedal remains rock-hard. (Added cost: The full repair cost becomes unavoidable, plus the cost of a tow truck.)

Diagnosis Steps

1. Scan for All Trouble Codes
   Use an OBD-II scanner capable of reading ABS/VSC codes. Document all codes. On Toyota/Lexus, C1256, C1391, and C1253 confirm actuator failure. On Jeep/Ram, P258B confirms a vacuum pump issue.
   Tools: ['OBD-II Scanner'] (Basic)
2. Check Brake System Fuses and Relays
   Locate the engine bay fuse box and check ABS/brake fuses. On Ram 1500s, check fuse #F33 (30A); on Jeep Gladiators, check F35 (30A). A blown fuse proves the pump motor shorted and requires replacement.
   Tools: ['Multimeter', 'Needle-nose pliers'] (Basic)
3. Listen to the Pump Motor
   Turn the vehicle 'On'. Listen for the electric pump in the engine bay. A pump running continuously or cycling every 15-30 seconds without brake pedal input confirms a pressure or vacuum leak.
   Tools: ['None'] (Basic)
4. Monitor Accumulator Pressure via Live Data
   Access ABS/VSC live data with a professional scan tool. Monitor 'Accumulator Pressure Sensor' voltage. A healthy system holds steady between 3.2V and 4.0V. A rapid voltage drop (e.g., > 0.55V in 30 seconds) after the pump shuts off confirms an internal leak.
   Tools: ['Professional Scan Tool (e.g., Toyota Techstream)'] (Advanced)
5. Perform a Vacuum System Integrity Test (FCA Vehicles)
   For Jeep/Ram with C1252-92, inspect all vacuum lines between the intake, pump, and booster for cracks or chafing. Use a vacuum gauge to test check valves. A line leak destroys new pumps.
   Tools: ['Vacuum Gauge', 'Smoke Machine'] (Intermediate)
6. Measure Pump Motor Resistance
   If the pump fails to run but the fuse is good, disconnect the motor harness. Measure resistance between the power (MT+) and ground (MT-) terminals. Resistance above 2 Ω or an open circuit indicates a failed motor.
   Tools: ['Multimeter', 'Basic hand tools'] (Advanced)
7. Test the Pump Motor and Relay via Active Test
   Use a scan tool's 'Active Test' to command the pump motor relay on and off. If the pump fails to run when commanded ON, the motor or relay failed. If it runs when commanded OFF, the relay is stuck closed.
   Tools: ['Professional Scan Tool'] (Advanced)
8. Inspect for External Leaks
   Visually inspect the brake master cylinder, brake lines, and actuator assembly for brake fluid leaks. External leaks are less common for this code but must be ruled out.
   Tools: ['Flashlight'] (Basic)

When This Code Triggers (Freeze-Frame Conditions)

• DTC That Caused Freeze Frame: C1252 (Confirms which code triggered the data snapshot.)
• Pump Motor Status: ON (Sets when the pump motor remains continuously ON for an excessive time period (e.g., > 90 seconds).)
• Accumulator Pressure Sensor (Voltage): < 3.2V (Voltage fails to reach the 'pump off' threshold, proving the system cannot build sufficient pressure.)
• Vehicle State: Any (Idle, Driving, Key-On) (This fault triggers anytime the vehicle is on and the system fails to hold pressure, even when parked.)

Related Codes

• C1256 — Means 'Accumulator Low Pressure'. Appears with C1252 on Toyota/Lexus systems. The pump runs too long (C1252) because it cannot build pressure (C1256). C1256 is the result; C1252 is the ECU's attempt to fix it.
• C1391 — Means 'Abnormal Leak in Accumulator'. Points directly to the internal pressure leak causing the pump to overwork (C1252) and resulting in low pressure (C1256).
• C1253 — Means 'Pump Motor Relay Malfunction'. Appears when the overworked pump stresses the relay circuit, or a stuck relay forces the pump to run continuously.
• P258B — Means 'Electronic Vacuum Pump Performance'. An FCA-specific code appearing with C1252-92. Both point to auxiliary vacuum pump failure.

Climate & Environmental Factors

• Cold Weather: C1252 and C1256 codes appear more frequently in temperatures below 20°F (-7°C). Cold causes internal actuator seals to contract, worsening pre-existing leaks and preventing pressure buildup on startup.
• High Humidity / Water Ingress: Older Jeep Wrangler (JK) electric vacuum pumps suffered water intrusion due to poor mounting locations, causing premature failure. Water contamination in connectors causes shorts and malfunctions.

How to Talk to a Mechanic About This Code

Say this: "I have a [Vehicle] with brake warning lights on, and my scanner shows code C1252. For Toyota/Lexus: 'I suspect the common brake actuator failure; please confirm an internal leak via live data before quoting a replacement.' For Ram/Jeep: 'I believe this is a C1252-92 for the vacuum pump. Please check fuse F33/F35 and inspect vacuum lines for leaks before quoting a new pump.'"

This language proves you are an informed customer. It directs the shop to the exact manufacturer-specific cause, saving diagnostic time and preventing unnecessary upsells.

Avoid saying:

• 'My brake light is on, can you just fix it?'
• 'I hear a weird noise when I brake.'
• 'My friend said it might be the brakes.'

Questions to ask before authorizing the repair:

• For Toyota/Lexus: Can you show me the live data confirming the accumulator pressure sensor voltage drops quickly?
• For Ram/Jeep: Did you find a blown fuse or a specific vacuum hose leak?
• Does the estimate include the mandatory computer-assisted brake bleed procedure?
• What is the warranty on the part and labor?

Where to Take It: Dealer vs Independent vs Chain

• Dealer: Best for Toyota/Lexus owners checking warranty/CSP coverage and FCA software updates. For out-of-pocket repairs, compare dealer quotes with independent specialists.
  Best for: Vehicles covered by Toyota/Lexus Customer Support Programs (CSPs), FCA (Jeep/Ram) vehicles requiring PCM software updates, Complex diagnostics requiring factory tools (Techstream)
  Downsides: Highest labor rates ($180-$250+ per hour), Only offers expensive OEM new parts (Typical cost: +50% vs. baseline)
• Independent Shop: Excellent choice for most C1252 repairs, saving 20-40% vs. the dealer. Ensure they specialize in hybrids for Toyota/Lexus repairs.
  Best for: Out-of-warranty Toyota/Lexus actuator replacements, Straightforward Ram/Jeep vacuum pump replacements, Hybrid vehicle specialists
  Downsides: Must verify they own a bidirectional scan tool for ABS bleeding, Quality varies; requires ASE certifications (Typical cost: +0% vs. baseline)
• Chain Shop: AVOID. This is a complex, critical safety repair. Chain shops lack the tools for the mandatory electronic bleed procedure.
  Best for: Checking fuses or inspecting vacuum hoses
  Downsides: Technicians lack specialized tools (Techstream) and experience for complex hydraulic repairs, High risk of misdiagnosis (Typical cost: -10% vs. baseline)

When to Walk Away From the Repair

If the estimated repair cost for the C1252 fault exceeds 50% of your vehicle's current private-party market value, consider alternatives.

• Car worth $5000, fix is $3500: Walk away. A $3,500 repair on a $5,000 Prius is a poor financial decision.
• Car worth $25000, fix is $400: Fix it. A $400 vacuum pump replacement on a $25,000 Ram 1500 is a routine repair.
• Car worth $8000, fix is $4000: Borderline. The repair is 50% of the car's value. Walk away unless the car has a brand-new hybrid battery and pristine maintenance history.

What Scan Tool You Need for This Code

Minimum: A scan tool capable of reading and clearing Anti-Lock Brake System (ABS) codes. Basic engine code readers cannot see C1252.

Proper diagnosis requires accessing the ABS module, viewing live brake data, and performing an automated ABS bleed. Cheap scanners lack these features.

Budget: BlueDriver Pro (~$119) — Reads and clears ABS codes and displays live data. It CANNOT perform the bidirectional control needed for an active test or the ABS bleed procedure.

Mid-range: Autel MaxiCheck Pro / Foxwell NT630 Plus (~$150-250) — Reads/clears ABS codes and performs the mandatory 'ABS Auto Bleed' function required after replacing a Toyota actuator or Ram pump.

Professional: Autel MaxiCOM MK808 / XTOOL D8 (~$500-1000) — Provides full bidirectional control. Commands the pump motor on/off, monitors accumulator pressure with real-time graphing, and performs dealer-level ABS bleeds and calibrations.

Rent vs buy: Auto parts stores rent basic ABS readers for initial diagnosis. If repairing a Toyota/Lexus yourself, you MUST buy a midrange tool capable of the automated bleed.

How to Clear the Code After You Fix It

1. Perform mandatory calibrations (e.g., computer-assisted brake bleed for Toyota/Lexus)
2. Use a compatible OBD-II scan tool to clear codes from the ABS/VSC module
3. Perform a complete drive cycle to verify the repair

Drive cycle (~30 minutes): After clearing codes, perform a drive cycle: 1) Cold start and idle for 3 minutes. 2) Drive in stop-and-go traffic for 15 minutes, making several full stops. 3) Drive at highway speeds (55-60 mph) for 10 minutes.

Readiness monitors affected: None. This is an ABS/Brake code and does not affect emissions readiness monitors.

Watch out for:

• The code returns immediately if the underlying leak or failed pump is not fixed.
• Clearing the code without repairing the vehicle is dangerous.
• Failing to perform the computer-assisted brake bleed on a Toyota/Lexus guarantees the code returns.

Will This Fail Emissions / State Inspection?

No — by itself this code doesn't fail OBD inspection (but it can keep readiness monitors from setting, which causes a separate fail).

• California: C1252 does not fail the OBD-II emissions scan, but inspectors fail the vehicle on the safety inspection due to the illuminated red brake warning light.
• New York: An illuminated red brake warning light or ABS light causes an automatic failure during the annual safety inspection.
• Texas: An illuminated red 'Brake' warning lamp causes the vehicle to fail the safety inspection.

Most Commonly Affected Vehicles

• Toyota Prius (2004-2015) — Widespread brake actuator assembly failure. Gen 3 (2010-2015) models were covered by Customer Support Program ZJB (10 years / 150,000 miles).
• Toyota Prius C (2012-2017) — Prone to internal actuator leaks. Covered by CSP 24TE01 (2015-2017) and TSB T-SB-0028-21 (2012-2014) when C1252, C1256, and C1391 are present.
• Toyota Prius V (2012-2017) — Experiences identical brake actuator failures. Dealer quotes range from $3,500 to $4,700. Covered by CSP 20TE07.
• Lexus CT200h (2011-2017) — Suffers the exact same brake actuator assembly failure as the Prius, triggering C1252, C1256, and C1391.
• Lexus RX450h (2010-2019) — Known for internal actuator leaks. Addressed by TSB L-SB-0033-20 (2010-2012), TSB L-SB-0011-23 (2016-2019), and CSP 23LE04.
• Toyota Land Cruiser (2008-2021) — Uses an electro-hydraulic booster prone to failure from worn carbon brushes in the pump motor. Codes C1252 and C1256 are common.
• Jeep Wrangler (JL) (2018-2024) — C1252-92 indicates electronic brake vacuum pump failure. TSBs S1805000006 and 18-048-22 recommend checking for PCM software updates before replacing parts.
• Ram 1500 (5th Gen) (2019-2025) — Code C1252-92 points to electronic vacuum pump failure. The pump motor shorts out and blows the 30A fuse in slot #33.

Manufacturer-Specific Notes

• Toyota / Lexus: This code is the hallmark of widespread brake actuator assembly failure on hybrids. Toyota issued numerous TSBs and CSPs (e.g., ZJB, 24TE01, 23LE04) extending warranties. Diagnosis requires C1252, C1256, and C1391.
• Chrysler / Jeep / Dodge / Ram (FCA): Code C1252-92 points to the auxiliary vacuum pump, not the hydraulic system. TSBs warn against replacing the ABS module. Diagnosis focuses on fuse #F33/#F35, vacuum lines, and PCM updates (TSB 18-048-22).
• Subaru: C1252 means 'Wheel Speed Sensor Signal Of One Of The Wheels'. It triggers from irregular wheel speed sensor signals and has zero connection to the brake booster pump.
• General Motors (Chevrolet / GMC / Cadillac): On GM vehicles with Continuously Variable Road Sensing Suspension (CVRSS), C1252 means 'Left Front Normal Force Malfunction'. It relates to the electronic suspension, not the brakes.

Real Owner Stories

2019 Ram 1500 with 38k miles - The Simple Fuse Fix

Owner experienced a hard brake pedal. A shop scanned code C1252-92.

What they tried:

1. Technician checked fuse #F33 (30A) and found it blown.
2. Replacing the fuse caused it to blow immediately, proving a short circuit.

Outcome: Disconnecting the vacuum pump eliminated the short. Installing a new factory vacuum pump resolved the issue.

Lesson: On a Ram/Jeep with C1252-92, always check the dedicated 30A vacuum pump fuse first. A blown fuse guarantees the pump motor shorted internally.

2016 Toyota Prius V with 261k miles - The Intermittent Nightmare

Dash lit up with Brake/ABS lights, loud alarm, and weak brakes. Codes C1252, C1253, and C1256 stored.

What they tried:

1. The problem resolved itself after a few miles.
2. A hybrid shop found no active faults but flushed the dirty brake fluid.

Outcome: The problem continued intermittently. Forum experts confirmed this is the classic progression of brake actuator failure.

Lesson: An intermittent C1252 on a Toyota hybrid is the beginning of a terminal failure. The system temporarily recovering does not mean it is fixed.

2017 Jeep Wrangler - The Misleading Smoke Test

Vehicle had codes C1252 and C0021. The vacuum pump failed to run.

What they tried:

1. A smoke test on the brake booster passed, showing no leaks.
2. Replaced the electronic vacuum pump and sensor, which failed to solve the issue.

Outcome: The technician replaced the entire brake booster assembly, resolving all codes.

Lesson: Standard smoke tests cannot detect internal failures within the brake booster. If replacing the pump and checking lines fails, the booster is the root cause.

Ram TRX - The Hidden Chafe Point

Owner got a C1252 code after engine work.

What they tried:

1. Checked the sensor, relay, and fuse #33; all passed.
2. Swapped the vacuum pump with a known-good unit, but the code remained.

Outcome: Discovered a factory flaw where a pulley rubbed a hole through a vacuum line. Repairing the line fixed the issue.

Lesson: Inspect the entire length of vacuum lines for chafing before buying a new pump. A hidden leak triggers the exact same code as a failed pump.

How to Prevent This Code From Triggering

• Perform regular brake fluid flushes (Every 2-3 years or 30,000 miles) — Brake fluid absorbs moisture over time. Moisture corrodes internal seals and metal components of the brake actuator, causing leaks and failure.
• Service and lubricate brake calipers/sliders (Every 1-2 years) — Hybrids use hydraulic brakes less frequently, causing caliper slide pins to seize from corrosion. Seized calipers cause uneven braking and system faults.
• Periodically inspect vacuum hoses (FCA vehicles) (During every oil change) — Vacuum leaks destroy Ram/Jeep electronic vacuum pumps. Inspect lines for cracks or chafing against pulleys to prevent premature pump failure.
• Address a weak 12V battery promptly (As needed) — Electronic brake modules are highly sensitive to voltage. A weak 12V battery causes communication errors and false C1252 codes.

Frequently Asked Questions

Is it safe to drive with code C1252?

No. This code indicates a critical power brake failure. You will experience a sudden, total loss of braking assistance, requiring an immediate tow to a shop.

Why is the repair for C1252 on my Toyota/Lexus so expensive?

The root cause is a failure of the entire brake actuator assembly, a complex hydraulic unit costing over $1,300. Labor takes 5-8 hours because it requires removing multiple components and performing a specialized computer-assisted brake bleed. Total dealer quotes routinely exceed $3,000.

My Toyota/Lexus has a C1252. Is this covered by a recall?

Toyota and Lexus issued multiple Customer Support Programs (CSPs) extending the warranty for this specific failure to 10 years or 150,000 miles. Contact a dealer with your VIN to verify active coverage under programs like ZJB (Prius) or 23LE04 (Lexus). If covered, the repair is free.

Can I fix code C1252 myself?

Do not attempt this DIY repair. It involves high-pressure hydraulics and requires a professional bidirectional scan tool to bleed and calibrate the ABS system. Mistakes guarantee complete brake failure.

Can I use a used brake actuator to save money?

Never buy a used Toyota/Lexus brake actuator. The failure stems from internal wear, meaning a used part is already degrading and will fail shortly after installation. Always buy a new OEM unit for this critical safety component.

My mechanic hit the pump motor and it started working again. Can I just replace the motor?

Tapping the motor temporarily bypasses worn internal brushes, but the motor wore out because an internal hydraulic leak overworked it. Replacing only the motor ignores the root cause. The new motor will overwork and fail prematurely.

What happens if I ignore code C1252?

The power brake system will fail completely and permanently. The overworked pump motor burns out, leaving you with a rock-hard brake pedal and dangerously long stopping distances. You will eventually require a tow and the full repair.

Why did my C1252 code come back after replacing the part?

On a Toyota/Lexus, a returning code means the mechanic failed to perform the mandatory computer-assisted brake bleed. On a Jeep/Ram, it indicates an undiagnosed vacuum leak destroyed the new pump. Always verify the root cause before replacing parts.

Key Takeaways

• Code C1252 indicates a critical power brake system failure; stop driving immediately to prevent a total loss of braking assist.
• On Toyota and Lexus hybrids (2004-2017), this code almost always means a failed brake actuator assembly requiring a $2,500 to $4,700 repair.
• On Jeep and Ram vehicles (2018+), code C1252-92 points to a failed electronic vacuum pump, often confirmed by a blown 30A fuse in slot F33 or F35.
• Never replace just the pump motor on a Toyota/Lexus; the motor burns out because of an internal hydraulic leak, so the entire actuator assembly must be replaced.