Code
C0551
Generic
C — Chassis
Longitudinal Acceleration Sensor Circuit/Open
Views:
UK: 22
EN: 39
RU: 27
AI status
Completed
Completed
100%
Causes
- Open or broken wiring in sensor signal, power or ground circuit
- Poor, corroded or loose connector at the longitudinal acceleration sensor
- Failed longitudinal acceleration (accelerometer) sensor
- Water intrusion or contamination of connector or sensor
- Blown fuse or lost reference voltage to the sensor
- Intermittent short to battery or ground in harness
Symptoms
- ABS, ESC/ESP or traction control warning lamp illuminated
- Stability/traction control disabled or operating only in a limited mode
- Reduced vehicle stability intervention (delayed or no ABS/ESP response)
- Possible diagnostic trouble codes stored for related sensors
- Unusual braking or stability behavior under hard maneuvers
What to check
- Retrieve and record all stored codes and freeze-frame data with a scan tool
- Visually inspect sensor, mounting and connector for corrosion, damage, or water intrusion
- Check for any blown fuses that feed the ABS/ESP system
- Backprobe the sensor connector to confirm reference voltage and ground present with ignition ON
- Wiggle test wiring and connectors while monitoring live sensor data or signal voltage for intermittency
- Perform continuity/resistance check from sensor connector to the ABS/ESP control module pins with ignition off
Signal parameters
- Typical sensor power reference: ~5 V supply (varies by manufacturer)
- Typical zero-g signal approx. mid-supply (≈2.5 V) for analog accelerometers; signal moves above/below mid-point under acceleration
- Signal may be analog voltage or communicated digitally (module-integrated accelerometer sending data over internal bus/CAN) — consult OEM data
- Open-circuit condition: signal line floats or shows no change with applied acceleration
- Resistance to sensor may show open or very high ohms if internal coil/element failed
Diagnostic algorithm
- Use a scan tool to confirm C0551 and note any related codes; clear the code and attempt to re-create to confirm persistence.
- Visually inspect the longitudinal accel sensor, mounting bracket and connector for damage, corrosion, water, or physical impact.
- With ignition ON (engine off), backprobe the sensor connector: verify reference voltage, ground continuity, and signal voltage (record values).
- Perform a wiggle/oscillation test on the wiring harness and connector while watching live sensor data or signal voltage to detect intermittent opens/shorts.
- With ignition off, check continuity between the sensor connector pins and the ABS/ESP module pins. Repair any open circuits or high-resistance connections.
- If wiring, connectors and power/grounds are good, substitute a known-good sensor or bench-test/replace the sensor per OEM procedure.
- After repair or sensor replacement, clear codes, perform a system relearn/calibration if required, and road-test to verify the code does not return.
- If fault persists after sensor replacement and wiring verified, consider module-side fault; consult manufacturer procedures for module diagnostics, reflashing or replacement.
Likely causes
- Damaged or disconnected sensor connector or wiring
- Sensor failure (internal open)
- Corroded connector pins or water ingress at sensor
- Loss of reference voltage or ground to sensor
Fault status
Status
Control module reports an open or missing signal from the longitudinal acceleration sensor circuit; stability/traction control functions may be limited or disabled until the circuit is repaired.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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Code
C0551
OPEL
C — Chassis
Variant Coding Not Programmed
Views:
UK: 4
EN: 11
RU: 8
AI status
Completed
Completed
100%
Causes
- Open or broken wiring in sensor signal, power or ground circuit
- Poor, corroded or loose connector at the longitudinal acceleration sensor
- Failed longitudinal acceleration (accelerometer) sensor
- Water intrusion or contamination of connector or sensor
- Blown fuse or lost reference voltage to the sensor
- Intermittent short to battery or ground in harness
Symptoms
- ABS, ESC/ESP or traction control warning lamp illuminated
- Stability/traction control disabled or operating only in a limited mode
- Reduced vehicle stability intervention (delayed or no ABS/ESP response)
- Possible diagnostic trouble codes stored for related sensors
- Unusual braking or stability behavior under hard maneuvers
What to check
- Retrieve and record all stored codes and freeze-frame data with a scan tool
- Visually inspect sensor, mounting and connector for corrosion, damage, or water intrusion
- Check for any blown fuses that feed the ABS/ESP system
- Backprobe the sensor connector to confirm reference voltage and ground present with ignition ON
- Wiggle test wiring and connectors while monitoring live sensor data or signal voltage for intermittency
- Perform continuity/resistance check from sensor connector to the ABS/ESP control module pins with ignition off
Signal parameters
- Typical sensor power reference: ~5 V supply (varies by manufacturer)
- Typical zero-g signal approx. mid-supply (≈2.5 V) for analog accelerometers; signal moves above/below mid-point under acceleration
- Signal may be analog voltage or communicated digitally (module-integrated accelerometer sending data over internal bus/CAN) — consult OEM data
- Open-circuit condition: signal line floats or shows no change with applied acceleration
- Resistance to sensor may show open or very high ohms if internal coil/element failed
Diagnostic algorithm
- Use a scan tool to confirm C0551 and note any related codes; clear the code and attempt to re-create to confirm persistence.
- Visually inspect the longitudinal accel sensor, mounting bracket and connector for damage, corrosion, water, or physical impact.
- With ignition ON (engine off), backprobe the sensor connector: verify reference voltage, ground continuity, and signal voltage (record values).
- Perform a wiggle/oscillation test on the wiring harness and connector while watching live sensor data or signal voltage to detect intermittent opens/shorts.
- With ignition off, check continuity between the sensor connector pins and the ABS/ESP module pins. Repair any open circuits or high-resistance connections.
- If wiring, connectors and power/grounds are good, substitute a known-good sensor or bench-test/replace the sensor per OEM procedure.
- After repair or sensor replacement, clear codes, perform a system relearn/calibration if required, and road-test to verify the code does not return.
- If fault persists after sensor replacement and wiring verified, consider module-side fault; consult manufacturer procedures for module diagnostics, reflashing or replacement.
Likely causes
- Damaged or disconnected sensor connector or wiring
- Sensor failure (internal open)
- Corroded connector pins or water ingress at sensor
- Loss of reference voltage or ground to sensor
Fault status
Status
Control module reports an open or missing signal from the longitudinal acceleration sensor circuit; stability/traction control functions may be limited or disabled until the circuit is repaired.
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