C1391
2 owner reports and 57 manufacturer filings across 41 model years from Lexus, Toyota.
Where C1391 shows up
Source: NHTSA manufacturer communications and complaintsShowing the 25 model years where C1391 appears most; it is on file for 41 in total.
A model year appears here because the code is named in its record, not because every one of these vehicles sets it. Counts are mentions in the federal files, not failure rates — nobody publishes the denominator.
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C1391 by make
The same record, one make at a time: the model years, bulletins and owner reports that name C1391 on that maker’s vehicles.
What it gets filed under
What owners said
Source: NHTSA complaint databaseOwners’ own words, one per nameplate, scrubbed of anything identifying. These are unverified reports filed with NHTSA — they are what was said, not a finding that it was true.
The vehicle was towed to an independent mechanic, where it was diagnosed with diagnostic trouble code C1391
This matches symptoms in Lexus TSB L-SB-0022-22 (DTC C1391: Abnormal leak in brake accumulator/accumulator assembly)
57 manufacturer filings name C1391. Start with what the maker wrote down.
A code names the test that failed, not the part. A bulletin that names it is often a diagnosis someone has already written down — quote its number at the service desk.
Manufacturer filings that name it
Source: NHTSA manufacturer communicationsService bulletins and campaigns whose filed summary names C1391.
- L-SB-0028-26 Service bulletin2026-09-30 · Service Brakes
- Some 2018 – 2023 model year LC 500, and LC 500h, 2021 – 2023 model year LC 500c, 2018 – 2023 model year LS 500, and LS 500h, 2015 model year RX 450h, and 2018 – 2022 model year RX 450h vehicles may exhibit a condition in which the brake, ABS, and/or TRAC warning lights are on and/or a Check VSC message displays. One or more of the following specific Diagnostic Trouble Codes (DTCs) C1391, C1252, C1
- T-SB-0014-25 Service bulletin2025-01-29 · Service Brakes
- Some 2017 – 2019 model year Highlander Hybrid vehicles may exhibit a condition in which the brake, ABS, and/or TRAC warning lights are on and/or a Check VSC message displays. One or more of the following specific Diagnostic Trouble Codes (DTCs): C1391, C1252, C1256, and/or C1253 will be stored in the vehicle memory to be used as verification. This condition may be caused by a small internal brake
- L-SB-0008-25 Service bulletin2025-01-29 · Service Brakes
- Some 2016 – 2018 model year GS 450h, 2013 – 2016 model year LS 600h, and 2018 – 2021 model year NX 300h vehicles may exhibit a condition in which the brake, ABS, and/or TRAC warning lights are on and/or a Check VSC message displays. One or more of the following specific Diagnostic Trouble Codes (DTCs) C1391, C1252, C1256, and/or C1253 will be stored in the vehicle memory to be used as verification
- 24TE01 Service campaign2024-11-04 · Service Brakes
- This Customer Support Program provides coverage as it applies to Brake Booster and Brake Booster Pump Assemblies on Certain 2014-2016 Model Year Highlander HV and certain 2017 Model Year Prius V Vehicles. The specific condition covered by this program is related to certain internal malfunctions of the Brake Booster Assembly. One or more of the following specific Diagnostic Trouble Codes (DTCs) C13
- LSB000824 Service bulletin2024-02-21 · Service Brakes
- TSB: Some 2014 ? 2017 model year CT 200h vehicles may exhibit a condition in which the brake, ABS, and/or TRAC warning lights are on and/or a Check VSC message displays. One or more of the following specific Diagnostic Trouble Codes (DTCs) C1391, C1252, C1256, and/or C1253 will be stored in the vehicle memory to be used as verification. This condition may be caused by a small internal brake fluid
- TSB000924 Service bulletin2024-02-21 · Service Brakes
- TSB: Some 2014 ? 2016 model year Highlander Hybrid vehicles may exhibit a condition in which the brake, ABS, and/or TRAC warning lights are on and/or a Check VSC message displays. One or more of the following specific Diagnostic Trouble Codes (DTCs): C1391, C1252, C1256, and/or C1253 will be stored in the vehicle memory to be used as verification. This condition may be caused by a small internal b
What C1391 means
Source: SAE J2012 / OBD-IIC1391 is a manufacturer-specific code: the second character is a 1, which under the OBD-II standard hands the definition to whoever built the vehicle. The same code can mean one thing on a Ford and something unrelated on a Hyundai. Any site that prints a single definition for it is guessing.
A stored code names the test that failed, never the part that caused it. It is the starting point of a diagnosis, not its conclusion — the same code has several possible causes and the cheap one is not always right.
Common questions about C1391
Source: NHTSA files and the OBD-II standardWhy does this page not define C1391?
Because it cannot be defined honestly. The second character of a trouble code says who owns its meaning, and a 1 or a 3 hands that to the manufacturer. Sites that print one definition for a manufacturer-specific code are showing you one automaker's meaning and hoping it is yours.
Can I keep driving with C1391 stored?
Nobody can answer that from the code alone, and a site that does is guessing. A steady light means a fault was logged and the car should be checked soon; a flashing light means a severe misfire — slow down and get it seen as soon as possible, because severe misfire can quickly damage the catalytic converter. The safe read of this page is the mileage and the components, not permission.
Does a code mean the car is recalled?
No. Recalls are filed by campaign and matched by VIN, and none of them are triggered by a scan tool. If you want to know whether an open recall applies to one specific vehicle, check the VIN at nhtsa.gov/recalls — that is the only source that settles it.
Why do the counts here differ from other sites?
Because these are not estimates. Every number on this page is a count of documents in NHTSA's own files: manufacturer communications that name the code in their filed summary, and owner complaints that name it in the narrative. We do not model, weight or extrapolate them.
Will clearing the code fix it?
Clearing turns the light off and erases the freeze-frame data a technician would have used to work out what happened. If the condition is still there the code returns, usually within a few drive cycles, and the diagnosis now starts from less information than before.