Code
C0048
Generic
C — Chassis
Brake Booster Travel Sensor
AI status
Completed
Completed
100%
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
Similar codes
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Code
C0048
HYUNDAI
C — Chassis
Brake Booster Travel Sensor (Subfault)
AI status
Completed
Completed
100%
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
Similar codes
Repair manuals
Manual library for HYUNDAI
371
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