How severe is fault code C1955?

Serious — Stop or limit driving

OBD Code C1955: Steering Angle Sensor Circuit Open

Q: What does OBD code C1955 mean?

Steering Angle Sensor Circuit Open. The steering angle sensor has lost its electrical connection to the ECU, like a phone with a broken charging cable that can't communicate its battery level. The vehicle's stability and steering control systems can't function properly without knowing the wheel position.

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What This Actually Means

In plain language — no jargon

The steering angle sensor has lost its electrical connection to the ECU, like a phone with a broken charging cable that can't communicate its battery level. The vehicle's stability and steering control systems can't function properly without knowing the wheel position.

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Symptoms You May Notice

3 known symptoms for this code

Electronic stability control (ESC) or traction control warning lights illuminate

Loss of power steering assistance or steering feels heavy

Vehicle may not start or exhibits limp-mode behavior

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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors the steering angle sensor's voltage signal, which typically ranges 0.5V to 4.5V depending on steering wheel position. When the circuit opens, the sensor stops sending data and voltage drops to 0V or becomes erratic, triggering a circuit-open fault. The ECU uses this input to coordinate stability control, lane-keeping assist, and adaptive steering systems.

Voltage & Parameter Thresholds

Parameter	Normal Range	Fault Condition
Sensor voltage signal	0.5V to 4.5V (proportional to steering angle)	0V or no signal detected for >2 seconds
Signal continuity	Continuous analog waveform	Open circuit or intermittent connection

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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex

1

Steering angle sensor connector

Inspect and reseat the connector at the steering column or behind the steering wheel; clean corrosion with contact cleaner.

2

Wiring harness (steering angle sensor circuit)

Check the wiring for cuts, damage, or pinched cables between the sensor and ECU; repair or replace damaged sections.

3

Steering angle sensor

Replace the sensor unit itself if connectors and wiring are intact; requires steering wheel removal on most vehicles.

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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code C1955 is classified as a serious fault. If your check engine light is flashing — not just steady — pull over safely and do not continue driving. A flashing CEL indicates an active misfire or critical failure that can cause catalytic converter damage within minutes or permanent engine harm within miles. Contact a certified mechanic immediately. Do not attempt roadside repairs on high-severity codes unless you are trained to do so.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.

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How to Clear Code C1955

What happens after you fix the fault

Once the fault is repaired, C1955 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When

Fault has been diagnosed and repaired
You want to confirm the repair worked
Code appeared after a sensor was cleaned

⚠️ Do Not Clear When

Preparing for an emissions/PUC test
Root cause is still undiagnosed
Check engine light is flashing

Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.