C1559

Code

Generic C — Chassis

Brake Pressure Sensor Circuit Range/Performance

Brand: Generic

Type: C — Chassis

Views: UK: 5 EN: 9 RU: 4

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Faulty brake pressure (hydraulic) sensor
Open, shorted, grounded or intermittent wiring between sensor and ABS module
Corroded or loose connector / poor pin contact
Low or contaminated brake fluid or air in the hydraulic system affecting sensor reading
Failed ABS hydraulic unit or internal sensor harness
Faulty ABS/ESC control module or software/calibration issue

Symptoms

ABS and/or traction control warning lamp illuminated
Brake warning lamp may also be on
Reduced or disabled ABS/ESC operation
Possible changes in pedal feel during ABS events
Diagnostic trouble codes stored; may be intermittent

What to check

Read ABS module codes and freeze frame / event data with a capable scan tool
Check for other related codes (wheel speed sensors, brake switch, hydraulic unit)
Visually inspect sensor connector and wiring for damage, corrosion, pin push-out or chafing
Verify proper brake fluid level and condition; look for contamination or leaks
Measure sensor supply and signal voltages with ignition on and while applying brake pressure
Wiggle test harness while monitoring live data to reproduce fault

Signal parameters

Typical sensor supply: 5 V reference (varies by manufacturer) or dedicated regulated supply
Typical output signal range (resistive/voltage type): approx. 0.5 V to 4.5 V proportional to pressure
Some systems use frequency or CAN/serial message from hydraulic unit instead of analog voltage
Signal should change smoothly with applied hydraulic pressure; no sudden drops or erratic jumps
Expected impedance/resistance depends on sensor type — consult OEM specs

Diagnostic algorithm

Use a scan tool to record the code(s) and live data, then clear codes and attempt to re-create the fault.
Visually inspect wiring and connectors at the brake pressure sensor and ABS module; repair any damage.
With harness connected, back-probe the sensor connector and verify reference supply, ground, and signal voltages with ignition on and while applying brake pressure. Compare to OEM expected ranges.
If signal does not change with pressure, isolate by applying pressure to the hydraulic circuit (service brake or use a pressure gauge) while monitoring the sensor output.
Perform continuity and resistance checks for short to ground or short to battery on the sensor wiring.
If wiring and supply are good but signal remains out of range, replace or bench-test the pressure sensor/hydraulic modulator per manufacturer procedure.
If sensor and wiring test good, check ABS module inputs and grounds; consult manufacturer for module tests or software updates.
After repair or replacement, clear codes and perform a road test or system exercise to confirm the issue is resolved.

Likely causes

Damaged wiring or poor connector at the brake pressure sensor
Failed brake pressure transducer (electrical) inside hydraulic modulator
Contaminated or low brake fluid causing incorrect pressure behaviour
Intermittent connection causing signal to go out of expected range

Fault status

⚠️ Status

Brake Pressure Sensor Circuit Range/Performance — the ABS/ESC control module detected the brake pressure sensor output is outside the expected range or behaving inconsistently. May disable ABS/ESC functionality until resolved.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours