What Does C1159 Mean?
This code indicates the ABS or brake control module has detected that the hydraulic fluid pressure/flow sensor circuit is shorted to ground. The pressure sensor monitors ABS hydraulic system pressure, and a short to ground causes the module to read a constant low or zero pressure signal, which may falsely indicate a hydraulic system failure.
Safety Warning
ABS is likely disabled due to false low pressure indication. Conventional braking still functions but anti-lock capability is lost. Repair promptly.
Common Causes
35%
Damaged wiring from the hydraulic pressure sensor to the control module, chafed against a metal bracket or body panel
25%
Failed hydraulic pressure sensor with internal short to ground
25%
Corroded connector at the pressure sensor from brake fluid seepage or moisture exposure
15%
Pinched wiring at the ABS hydraulic modulator mounting area
Diagnostic Steps
1
Step 1: Disconnect the hydraulic pressure sensor and check if the code changes to an open circuit code. If so, the sensor is internally shorted.
2
Step 2: With the sensor disconnected, measure resistance from the signal wire to chassis ground at the control module connector. Low resistance confirms a harness short.
3
Step 3: Visually inspect the harness from the sensor to the module for chafing, pinched areas, or brake fluid contamination.
4
Step 4: Test the sensor by measuring resistance between signal pin and sensor ground/housing. Compare to manufacturer specifications.
5
Step 5: Repair or replace the faulty component, clear codes, and verify proper pressure readings in live data during brake application.
Estimated Repair Cost
$150 - $600
Parts + labor, varies by vehicle and location
This code indicates the ABS or brake control module has detected that the hydraulic fluid pressure/flow sensor circuit is shorted to ground. The pressure sensor monitors ABS hydraulic system pressure, and a short to ground causes the module to read a constant low or zero pressure signal, which may f...
The most common cause of C1159 (Hydraulic Fluid Pressure/ Flow Circuit Short to Gnd) is: Damaged wiring from the hydraulic pressure sensor to the control module, chafed against a metal bracket or body panel
Typical repair costs for C1159 range from $150 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
ABS is likely disabled due to false low pressure indication. Conventional braking still functions but anti-lock capability is lost. Repair promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1159 to identify the root cause.
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Quick Info
Category
Chassis
System
ABS Hydraulic Pressure System
Difficulty
Type
Manufacturer
Recommended Tools
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