Code
C0550
Generic
C — Chassis
Vacuum Sensor B Circuit High
Views:
UK: 30
EN: 33
RU: 19
AI status
Completed
Completed
100%
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
- Obtain complete vehicle service data and wiring diagram for the vacuum sensor circuit before testing.
- Confirm the code and any freeze-frame/live data with a scan tool. Note sensor voltage value shown.
- 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.
- 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.
- Verify sensor ground continuity and low resistance to chassis ground/ECU ground.
- 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.
- Perform continuity checks from the harness signal wire to the ECU connector; check for short to battery and short to ground.
- Repair any damaged wiring, pins, or connectors found. Replace sensor if bench/vehicle checks indicate failure.
- After repair, clear codes, retest system and verify live data under various operating conditions. Confirm no recurrence of C0550.
- 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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Code
C0550
HUMMER
C — Chassis
ECU Malfunction - internal write / checksum malfunction
Views:
UK: 12
EN: 12
RU: 7
AI status
Completed
Completed
100%
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
- Obtain complete vehicle service data and wiring diagram for the vacuum sensor circuit before testing.
- Confirm the code and any freeze-frame/live data with a scan tool. Note sensor voltage value shown.
- 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.
- 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.
- Verify sensor ground continuity and low resistance to chassis ground/ECU ground.
- 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.
- Perform continuity checks from the harness signal wire to the ECU connector; check for short to battery and short to ground.
- Repair any damaged wiring, pins, or connectors found. Replace sensor if bench/vehicle checks indicate failure.
- After repair, clear codes, retest system and verify live data under various operating conditions. Confirm no recurrence of C0550.
- 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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Code
C0550
HYUNDAI
C — Chassis
ECM Error
Views:
UK: 18
EN: 14
RU: 12
AI status
Completed
Completed
100%
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
- Obtain complete vehicle service data and wiring diagram for the vacuum sensor circuit before testing.
- Confirm the code and any freeze-frame/live data with a scan tool. Note sensor voltage value shown.
- 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.
- 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.
- Verify sensor ground continuity and low resistance to chassis ground/ECU ground.
- 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.
- Perform continuity checks from the harness signal wire to the ECU connector; check for short to battery and short to ground.
- Repair any damaged wiring, pins, or connectors found. Replace sensor if bench/vehicle checks indicate failure.
- After repair, clear codes, retest system and verify live data under various operating conditions. Confirm no recurrence of C0550.
- 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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Code
C0550
OPEL
C — Chassis
Electronic Control Unit Not Programmed (ECU)
Views:
UK: 2
EN: 5
RU: 4
AI status
Completed
Completed
100%
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
- Obtain complete vehicle service data and wiring diagram for the vacuum sensor circuit before testing.
- Confirm the code and any freeze-frame/live data with a scan tool. Note sensor voltage value shown.
- 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.
- 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.
- Verify sensor ground continuity and low resistance to chassis ground/ECU ground.
- 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.
- Perform continuity checks from the harness signal wire to the ECU connector; check for short to battery and short to ground.
- Repair any damaged wiring, pins, or connectors found. Replace sensor if bench/vehicle checks indicate failure.
- After repair, clear codes, retest system and verify live data under various operating conditions. Confirm no recurrence of C0550.
- 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
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email