B1570

Lamp Headlamp High-Beam Circuit Short To Ground

Body Chassis/Safety Lighting circuit 🟢 Low — Fix at next service ✅ Safe to Drive
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What This Actually Means

In plain language — no jargon

The high-beam headlamp circuit is shorted directly to ground, preventing the headlamps from illuminating properly. Think of it like a short circuit in a flashlight where the battery drains instantly instead of powering the bulb.

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Symptoms You May Notice

3 known symptoms for this code
High-beam headlamps not illuminating or dimmer than normal
High-beam indicator lamp on dashboard not functioning
Potential blown fuse in headlamp circuit or flickering behavior
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors the voltage and current draw through the high-beam headlamp circuit. When the circuit shorts to ground, current draw spikes to maximum while voltage drops near zero. The ECU detects this abnormal current condition and triggers the fault code.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
High-beam circuit voltage 12-13.5V when activated Below 2V or excessive current draw (>15A)
Circuit resistance 4-8 ohms per headlamp Less than 1 ohm (short to ground)
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
High-beam headlamp fuse
Locate and replace the blown fuse in the fuse box; check the owner's manual for location and amperage rating.
2
High-beam headlamp wiring harness
Inspect the wiring loom for damage, pinches, or exposed wire causing ground contact and repair or replace the damaged section.
3
High-beam headlamp bulb and socket assembly
Remove and inspect the bulb socket for corrosion or moisture, clean contacts or replace the entire bulb/socket assembly if damaged.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code B1570 is a low-severity fault. Your vehicle is generally safe to drive to a workshop for diagnosis. However, do not ignore it indefinitely — low-severity codes often indicate developing problems that become expensive if neglected. Book a diagnostic appointment within 2–4 weeks. If you notice any additional symptoms (rough running, power loss, unusual smells), treat it as higher priority.

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 B1570

What happens after you fix the fault

Once the fault is repaired, B1570 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.