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Home / DTC / C0550 — Vacuum Sensor B Circuit High

C0550 — Vacuum Sensor B Circuit High

Detailed page for trouble code C0550.

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22,491specific
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Code

C0550

Generic C — Chassis

Vacuum Sensor B Circuit High

Brand: Generic
Type: C — Chassis
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the Vacuum Sensor B signal wire
  • Failed vacuum sensor (internal fault)
  • Poor or corroded connector or pin at the sensor
  • Open or damaged wiring (intermittent high due to floating circuit)
  • Faulty sensor ground or reference supply (module side)
  • Faulty control module (rare)

Symptoms

  • ABS, traction control, or brake warning lamp illuminated (if module monitors vacuum sensor)
  • Brake assist or power brake feel reduced or inconsistent on some systems
  • Diagnostic trouble code stored and possibly other related codes
  • Possible limp/limited performance of systems that depend on vacuum input
  • No obvious mechanical symptoms in some cases (electrical only)

What to check

  • Retrieve freeze-frame and full DTC list; note any related codes
  • Visual inspection of vacuum sensor, connector, and harness for damage or corrosion
  • Wiggle test harness while monitoring live data or DTCs for intermittent faults
  • Measure key-on reference voltage and ground at sensor connector
  • Backprobe signal wire to measure voltage with ignition ON (engine OFF) and during cranking/running if safe
  • Check for continuity and shorts to battery (+12V) on the signal wire

Signal parameters

  • Reference supply (typical): ~5 V (varies by manufacturer)
  • Expected signal range (typical): ~0.5–4.5 V analog (manufacturer-specific)
  • High condition defined as signal above expected maximum (eg. >4.5 V) or stuck near battery voltage
  • Ground continuity: low ohms between sensor ground and chassis/ECU ground
  • No high-frequency PWM expected unless specified by manufacturer — check service data

Diagnostic algorithm

  1. Obtain complete vehicle service data and wiring diagram for the vacuum sensor circuit before testing.
  2. Confirm the code and any freeze-frame/live data with a scan tool. Note sensor voltage value shown.
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to module for damage, pin push-out, corrosion, or contact with moving/heat sources.
  4. With ignition ON (engine OFF), backprobe the sensor connector: verify reference voltage (~5 V) and sensor signal voltage. A signal near battery voltage indicates a short to +12 V.
  5. Verify sensor ground continuity and low resistance to chassis ground/ECU ground.
  6. If signal is high, disconnect the sensor and re-check the signal at the harness connector: if it remains high, suspect wiring short to 12 V or ECU. If it goes to open/low, suspect sensor internal failure.
  7. Perform continuity checks from the harness signal wire to the ECU connector; check for short to battery and short to ground.
  8. Repair any damaged wiring, pins, or connectors found. Replace sensor if bench/vehicle checks indicate failure.
  9. After repair, clear codes, retest system and verify live data under various operating conditions. Confirm no recurrence of C0550.
  10. If wiring and sensor test OK but code persists, consult manufacturer service documentation for module tests or consider module replacement as a last resort.

Likely causes

  • Shorted signal wire to 12V (most common for a 'High' circuit)
  • Corroded/loose connector at the sensor or module
  • Defective vacuum sensor
  • Bad ground or blown reference fuse
  • Control module output/monitor circuit fault (least common)

Fault status

⚠️ Status
Vacuum Sensor B circuit voltage higher than the expected range. Possible short to battery, failed sensor, poor connector/ground, or wiring fault. May affect brake/ABS systems that use vacuum input.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

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C0551 C0552 C0553 C1236
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Code

C0550

HUMMER C — Chassis

ECU Malfunction - internal write / checksum malfunction

Brand: HUMMER
Type: C — Chassis
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the Vacuum Sensor B signal wire
  • Failed vacuum sensor (internal fault)
  • Poor or corroded connector or pin at the sensor
  • Open or damaged wiring (intermittent high due to floating circuit)
  • Faulty sensor ground or reference supply (module side)
  • Faulty control module (rare)

Symptoms

  • ABS, traction control, or brake warning lamp illuminated (if module monitors vacuum sensor)
  • Brake assist or power brake feel reduced or inconsistent on some systems
  • Diagnostic trouble code stored and possibly other related codes
  • Possible limp/limited performance of systems that depend on vacuum input
  • No obvious mechanical symptoms in some cases (electrical only)

What to check

  • Retrieve freeze-frame and full DTC list; note any related codes
  • Visual inspection of vacuum sensor, connector, and harness for damage or corrosion
  • Wiggle test harness while monitoring live data or DTCs for intermittent faults
  • Measure key-on reference voltage and ground at sensor connector
  • Backprobe signal wire to measure voltage with ignition ON (engine OFF) and during cranking/running if safe
  • Check for continuity and shorts to battery (+12V) on the signal wire

Signal parameters

  • Reference supply (typical): ~5 V (varies by manufacturer)
  • Expected signal range (typical): ~0.5–4.5 V analog (manufacturer-specific)
  • High condition defined as signal above expected maximum (eg. >4.5 V) or stuck near battery voltage
  • Ground continuity: low ohms between sensor ground and chassis/ECU ground
  • No high-frequency PWM expected unless specified by manufacturer — check service data

Diagnostic algorithm

  1. Obtain complete vehicle service data and wiring diagram for the vacuum sensor circuit before testing.
  2. Confirm the code and any freeze-frame/live data with a scan tool. Note sensor voltage value shown.
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to module for damage, pin push-out, corrosion, or contact with moving/heat sources.
  4. With ignition ON (engine OFF), backprobe the sensor connector: verify reference voltage (~5 V) and sensor signal voltage. A signal near battery voltage indicates a short to +12 V.
  5. Verify sensor ground continuity and low resistance to chassis ground/ECU ground.
  6. If signal is high, disconnect the sensor and re-check the signal at the harness connector: if it remains high, suspect wiring short to 12 V or ECU. If it goes to open/low, suspect sensor internal failure.
  7. Perform continuity checks from the harness signal wire to the ECU connector; check for short to battery and short to ground.
  8. Repair any damaged wiring, pins, or connectors found. Replace sensor if bench/vehicle checks indicate failure.
  9. After repair, clear codes, retest system and verify live data under various operating conditions. Confirm no recurrence of C0550.
  10. If wiring and sensor test OK but code persists, consult manufacturer service documentation for module tests or consider module replacement as a last resort.

Likely causes

  • Shorted signal wire to 12V (most common for a 'High' circuit)
  • Corroded/loose connector at the sensor or module
  • Defective vacuum sensor
  • Bad ground or blown reference fuse
  • Control module output/monitor circuit fault (least common)

Fault status

⚠️ Status
Vacuum Sensor B circuit voltage higher than the expected range. Possible short to battery, failed sensor, poor connector/ground, or wiring fault. May affect brake/ABS systems that use vacuum input.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

Similar codes

C0551 C0552 C0553 C1236
Repair manuals

Manual library for HUMMER

138

Browse 138 HUMMER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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Code

C0550

HYUNDAI C — Chassis

ECM Error

Brand: HYUNDAI
Type: C — Chassis
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the Vacuum Sensor B signal wire
  • Failed vacuum sensor (internal fault)
  • Poor or corroded connector or pin at the sensor
  • Open or damaged wiring (intermittent high due to floating circuit)
  • Faulty sensor ground or reference supply (module side)
  • Faulty control module (rare)

Symptoms

  • ABS, traction control, or brake warning lamp illuminated (if module monitors vacuum sensor)
  • Brake assist or power brake feel reduced or inconsistent on some systems
  • Diagnostic trouble code stored and possibly other related codes
  • Possible limp/limited performance of systems that depend on vacuum input
  • No obvious mechanical symptoms in some cases (electrical only)

What to check

  • Retrieve freeze-frame and full DTC list; note any related codes
  • Visual inspection of vacuum sensor, connector, and harness for damage or corrosion
  • Wiggle test harness while monitoring live data or DTCs for intermittent faults
  • Measure key-on reference voltage and ground at sensor connector
  • Backprobe signal wire to measure voltage with ignition ON (engine OFF) and during cranking/running if safe
  • Check for continuity and shorts to battery (+12V) on the signal wire

Signal parameters

  • Reference supply (typical): ~5 V (varies by manufacturer)
  • Expected signal range (typical): ~0.5–4.5 V analog (manufacturer-specific)
  • High condition defined as signal above expected maximum (eg. >4.5 V) or stuck near battery voltage
  • Ground continuity: low ohms between sensor ground and chassis/ECU ground
  • No high-frequency PWM expected unless specified by manufacturer — check service data

Diagnostic algorithm

  1. Obtain complete vehicle service data and wiring diagram for the vacuum sensor circuit before testing.
  2. Confirm the code and any freeze-frame/live data with a scan tool. Note sensor voltage value shown.
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to module for damage, pin push-out, corrosion, or contact with moving/heat sources.
  4. With ignition ON (engine OFF), backprobe the sensor connector: verify reference voltage (~5 V) and sensor signal voltage. A signal near battery voltage indicates a short to +12 V.
  5. Verify sensor ground continuity and low resistance to chassis ground/ECU ground.
  6. If signal is high, disconnect the sensor and re-check the signal at the harness connector: if it remains high, suspect wiring short to 12 V or ECU. If it goes to open/low, suspect sensor internal failure.
  7. Perform continuity checks from the harness signal wire to the ECU connector; check for short to battery and short to ground.
  8. Repair any damaged wiring, pins, or connectors found. Replace sensor if bench/vehicle checks indicate failure.
  9. After repair, clear codes, retest system and verify live data under various operating conditions. Confirm no recurrence of C0550.
  10. If wiring and sensor test OK but code persists, consult manufacturer service documentation for module tests or consider module replacement as a last resort.

Likely causes

  • Shorted signal wire to 12V (most common for a 'High' circuit)
  • Corroded/loose connector at the sensor or module
  • Defective vacuum sensor
  • Bad ground or blown reference fuse
  • Control module output/monitor circuit fault (least common)

Fault status

⚠️ Status
Vacuum Sensor B circuit voltage higher than the expected range. Possible short to battery, failed sensor, poor connector/ground, or wiring fault. May affect brake/ABS systems that use vacuum input.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

Similar codes

C0551 C0552 C0553 C1236
371

Browse 371 HYUNDAI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

HYUNDAI

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+100 karma for a short comment :)
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Code

C0550

OPEL C — Chassis

Electronic Control Unit Not Programmed (ECU)

Brand: OPEL
Type: C — Chassis
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the Vacuum Sensor B signal wire
  • Failed vacuum sensor (internal fault)
  • Poor or corroded connector or pin at the sensor
  • Open or damaged wiring (intermittent high due to floating circuit)
  • Faulty sensor ground or reference supply (module side)
  • Faulty control module (rare)

Symptoms

  • ABS, traction control, or brake warning lamp illuminated (if module monitors vacuum sensor)
  • Brake assist or power brake feel reduced or inconsistent on some systems
  • Diagnostic trouble code stored and possibly other related codes
  • Possible limp/limited performance of systems that depend on vacuum input
  • No obvious mechanical symptoms in some cases (electrical only)

What to check

  • Retrieve freeze-frame and full DTC list; note any related codes
  • Visual inspection of vacuum sensor, connector, and harness for damage or corrosion
  • Wiggle test harness while monitoring live data or DTCs for intermittent faults
  • Measure key-on reference voltage and ground at sensor connector
  • Backprobe signal wire to measure voltage with ignition ON (engine OFF) and during cranking/running if safe
  • Check for continuity and shorts to battery (+12V) on the signal wire

Signal parameters

  • Reference supply (typical): ~5 V (varies by manufacturer)
  • Expected signal range (typical): ~0.5–4.5 V analog (manufacturer-specific)
  • High condition defined as signal above expected maximum (eg. >4.5 V) or stuck near battery voltage
  • Ground continuity: low ohms between sensor ground and chassis/ECU ground
  • No high-frequency PWM expected unless specified by manufacturer — check service data

Diagnostic algorithm

  1. Obtain complete vehicle service data and wiring diagram for the vacuum sensor circuit before testing.
  2. Confirm the code and any freeze-frame/live data with a scan tool. Note sensor voltage value shown.
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to module for damage, pin push-out, corrosion, or contact with moving/heat sources.
  4. With ignition ON (engine OFF), backprobe the sensor connector: verify reference voltage (~5 V) and sensor signal voltage. A signal near battery voltage indicates a short to +12 V.
  5. Verify sensor ground continuity and low resistance to chassis ground/ECU ground.
  6. If signal is high, disconnect the sensor and re-check the signal at the harness connector: if it remains high, suspect wiring short to 12 V or ECU. If it goes to open/low, suspect sensor internal failure.
  7. Perform continuity checks from the harness signal wire to the ECU connector; check for short to battery and short to ground.
  8. Repair any damaged wiring, pins, or connectors found. Replace sensor if bench/vehicle checks indicate failure.
  9. After repair, clear codes, retest system and verify live data under various operating conditions. Confirm no recurrence of C0550.
  10. If wiring and sensor test OK but code persists, consult manufacturer service documentation for module tests or consider module replacement as a last resort.

Likely causes

  • Shorted signal wire to 12V (most common for a 'High' circuit)
  • Corroded/loose connector at the sensor or module
  • Defective vacuum sensor
  • Bad ground or blown reference fuse
  • Control module output/monitor circuit fault (least common)

Fault status

⚠️ Status
Vacuum Sensor B circuit voltage higher than the expected range. Possible short to battery, failed sensor, poor connector/ground, or wiring fault. May affect brake/ABS systems that use vacuum input.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

Similar codes

C0551 C0552 C0553 C1236
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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
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