C0091
Hydraulic Brake Pressure Sensor Circuit Range/Performance
The brake pressure sensor signal is outside the plausibility band relative to pedal application. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
The brake pressure sensor signal is outside the plausibility band relative to pedal application. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Common causes
- high
Sensor drift with age
One of the most commonly reported causes for this code — check this first.
Typical part cost: $220-1210
- low
Internal hydraulic block leak
Less common, but worth ruling out after the more likely causes.
Typical part cost: $220-1210
See all causes + fix costs
Create a free Wrenchify account to unlock the rest for C0091.
Unlock causesFree forever · No credit card
First things to check
- 1Confirm the code with a scan tool and check for additional related codes.
- 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.
Get the full step-by-step diagnosis
Create a free Wrenchify account to unlock the rest for C0091.
Unlock diagnosisFree forever · No credit card
Related codes
See related trouble codes
Create a free Wrenchify account to unlock the rest for C0091.
Unlock related codesFree forever · No credit card
Frequently asked questions
What does C0091 mean?
C0091 means "Hydraulic Brake Pressure Sensor Circuit Range/Performance". It is a generic OBD-II code that points to a fault in the chassis.
What are the most common causes of C0091?
sensor drift with age; internal hydraulic block leak; sensor element aged beyond calibration window — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.
Can I keep driving with this code?
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical. Use the Wrenchify app for a full diagnosis specific to your vehicle.
Get the full C0091 diagnosis for your vehicle
Year, make, model + step-by-step repair help — free plan included.