C0048

Code

Generic C — Chassis

Brake Booster Travel Sensor

Brand: Generic

Type: C — Chassis

Views: UK: 27 EN: 70 RU: 42

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Page language: EN

Causes

Faulty brake booster travel (pushrod position) sensor
Damaged, corroded or disconnected sensor connector or wiring harness
Poor sensor ground or missing reference voltage
Mechanical binding or incorrect pushrod adjustment at brake booster/pedal
Vacuum leak or failed vacuum assist reducing expected travel characteristics
Contaminated or failed sensor from fluid ingress or corrosion

Symptoms

Brake warning light and/or ABS/ESC malfunction indicator illuminated
Unusual or increased brake pedal travel (soft or low pedal)
Reduced or inconsistent power brake assist
ABS or stability control intervention on braking where not expected
Stored fault code C0048 and possibly related codes
Pedal feel changes that vary with engine vacuum (idle vs rev)

What to check

Scan for C0048 and any related freeze-frame or additional codes; record live data for pedal/travel sensor values
Perform a visual inspection of the sensor, connector and wiring to the booster for damage, corrosion, or pin push-out
Check brake fluid level and look for leaks around master cylinder/booster
Verify booster vacuum hose and one-way check valve integrity and listen for hissing vacuum leaks
Operate the brake pedal while observing pushrod/clevis for binding, abnormal angle, or loose fasteners
Backprobe the sensor connector and measure reference voltage, signal voltage and ground continuity

Signal parameters

Typical reference voltage: ~5.0 V (check manufacturer spec)
Signal output: varies with pedal position; commonly ~0.5–4.5 V across travel (should change smoothly)
Sensor resistance (if potentiometer type): commonly 2–10 kΩ (manufacturer specific)
Signal should be stable with engine off and change proportionally with pedal travel; no sudden jumps to 0 V or reference rail
If Hall-effect: open-circuit no load ≈ supply voltage; switching/analog output changes with movement

Diagnostic algorithm

Confirm C0048 present and note freeze-frame/live-data values and any additional codes.
Visually inspect booster, sensor, connector and harness for damage, corrosion or contamination.
With ignition ON (engine off), backprobe connector: verify sensor reference voltage (typically 5 V), ground continuity and expected resting signal value per vehicle spec.
Slowly press pedal while monitoring signal voltage; ensure smooth proportional change. Watch for intermittent drops to 0 V or rail voltages.
Measure continuity between sensor ground and chassis ground; repair poor ground if found.
Inspect pushrod, clevis, pedal pivot for mechanical binding or misadjustment; correct as needed and retest sensor output.
Check vacuum supply to booster, check valve function and for leaks. If booster not providing expected assist, pedal travel can differ and trigger the code.
If wiring or connector faults are found, repair and retest. If wiring is good but sensor output is erratic or out of range, replace sensor.
After repair clear codes and perform a road test and live-data monitoring to confirm correct behavior and no recurrence.
If code persists after sensor and wiring verified, consider control module fault and consult manufacturer service information for module tests.

Likely causes

Failed or intermittent booster travel sensor
Wiring connector corrosion, open or short to power/ground
Vacuum supply problem or failed booster causing abnormal travel
Mechanical interference at pedal/pushrod preventing normal movement

Fault status

⚠️ Status

Indicates the brake booster travel sensor circuit is reporting an implausible, missing or out-of-range signal. Brake assist or related systems may be affected; inspect electrical connections, sensor operation and booster/vacuum system promptly.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 2.5 hours