C1920

Led #1 Circuit Failure

Chassis Chassis/Safety LED/Lighting Control 🔴 Serious — Stop or limit driving 🚫 Do Not Drive
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What This Actually Means

In plain language — no jargon

The vehicle's diagnostic lighting system has detected a broken electrical circuit in LED light #1, similar to a light switch that no longer connects to the bulb. The ECU cannot properly control or verify this light's operation.

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Symptoms You May Notice

3 known symptoms for this code
LED indicator light not illuminating
Dashboard warning light stays on continuously
Electrical fault message displayed
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors the LED circuit for proper voltage and current draw during operation. It detects opens, shorts, or excessive resistance in the LED wiring or component itself. When the circuit deviates from expected electrical characteristics, the fault is logged.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
LED Circuit Current Draw 50-200 mA during illumination 0 mA (open) or >500 mA (short)
LED Circuit Voltage 12V nominal <5V or >14.5V sustained
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
LED bulb or module
Locate and replace the failed LED unit in the instrument cluster or exterior light assembly.
2
Wiring harness connector
Inspect and clean the LED circuit connectors for corrosion or loose terminals, then reseat firmly.
3
Fuse for LED circuit
Check the corresponding fuse in the fuse box and replace if blown or corroded.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code C1920 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 C1920

What happens after you fix the fault

Once the fault is repaired, C1920 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.