C1391: Abnormal Leak of Accumulator Pressure (manufacturer-specific)
3 vehicles · 1 makes · $1,200-$3,500 repair
Most Reported On
C1391 is an OBD-II diagnostic trouble code meaning “Abnormal Leak of Accumulator Pressure (manufacturer-specific).” C1391 is a manufacturer-specific brake code, documented mainly on Toyota and Lexus (often hybrid) models, indicating the brake control system detected an abnormal leak or loss of accumulator pressure in the hydraulic ABS/brake actuator. The accumulator stores pressurized brake fluid the system uses for power-assisted and ABS braking, and degraded internal seals can let it bleed down. Because this directly affects braking assist and can increase stopping distance, it is a serious fault that should be repaired promptly by a qualified shop. This code is most commonly reported on 2003-2009 Toyota 4Runner, 2006-2013 Toyota Highlander (Hybrid, Hybrid Limited), and 2012-2014 Toyota Camry (Hybrid LE, Hybrid XLE), with repair costs ranging from $1,200 to $3,500.
Common Causes
Typical Repair Cost
Based on 4 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose C1391, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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Vehicles Affected (3)
ABS Actuator / Master Cylinder Assembly Failure Triggering ABS/VSC/TRAC Lights and Brake Pump Noise
Brake Booster / Master Cylinder Internal Leak Causing Hard Pedal and Reduced Braking Assist
Hybrid Brake Booster / ABS Actuator Assembly Failure (Accumulator Leak) — C1391
Camry Hybrid Brake-Booster Internal Leak - T-SB-0130-19 / CSP ZKK
FAQ
What does C1391 mean?
C1391 stands for "Abnormal Leak of Accumulator Pressure (manufacturer-specific)." C1391 is a manufacturer-specific brake code, documented mainly on Toyota and Lexus (often hybrid) models, indicating the brake control system detected an abnormal leak or loss of accumulator pressure in the hydraulic ABS/brake actuator. The accumulator stores pressurized brake fluid the system uses for power-assisted and ABS braking, and degraded internal seals can let it bleed down. Because this directly affects braking assist and can increase stopping distance, it is a serious fault that should be repaired promptly by a qualified shop.
What are the most common causes of C1391?
The most common causes of C1391 are: Failing brake booster / master cylinder accumulator seals, Worn or leaking brake actuator assembly, Internal hydraulic leak in the ABS/brake actuator, Low brake fluid level, Aged or contaminated brake fluid, Faulty pump or pressure sensor within the actuator, Faulty brake control (skid control) ECU. The specific cause varies by vehicle.
How much does it cost to fix C1391?
Repair costs for C1391 range from $1,200 to $3,500, depending on the vehicle and root cause.
Which vehicles are affected by C1391?
Au7o has documented C1391 across 3 vehicle models from 1 manufacturers: Toyota.
Sources (9)
- ForumBrake Booster/Accumulator/Master Cylinder Assembly Replacement - Toyota 4Runner Forum
- ForumAlarm + VSC TRAC, TRAC OFF, ABS, Emergency Brake Lights On, no brakes - 2003 4Runner (ToyotaNation)
- ForumToyotaNation: Brake Problem master cylinder or booster?
- mediaiFixit: Why are my Brakes hard to push all of a sudden? 1990-1995 Toyota 4Runner
- article2006 Toyota Highlander Hybrid Brake Actuator Assembly Defect: complaints — CarComplaints
- ForumBrake Actuator Replacement (Highlander/RX Hybrid) — ClubLexus
- manufacturerGenuine Toyota Brake Actuator 44050-48191 (Highlander Hybrid)
- TSBToyota T-SB-0130-19: ABS/Brake and/or TRAC Warning Light On
- ManualToyota Customer Support Program ZKK: Camry Hybrid Brake Booster and Pump
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.