B1564

Door Ajar Circuit Open

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

In plain language — no jargon

The door ajar switch circuit has an open connection, meaning the car can't detect whether a door is open or closed—like a light switch with a broken wire. This prevents the ECU from receiving the signal it needs to monitor door status.

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Symptoms You May Notice

3 known symptoms for this code
Door ajar warning light stays on continuously
Interior lights don't turn on when door opens
Power windows or locks don't respond to door open/close events
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors voltage levels from door ajar switches installed in each door frame. When a door opens, the switch grounds the signal wire, sending a low-voltage state to the ECU. An open circuit means no voltage change is detected, triggering the fault code.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Door Switch Signal Voltage 0V (closed) to 12V (open) No voltage transition detected; circuit open
Circuit Continuity Less than 5 ohms resistance Infinite resistance or no continuity
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Door ajar switch
Inspect and clean the switch contacts in the affected door frame; if corroded, replace the switch.
2
Wiring harness connector
Check for loose, disconnected, or corroded connectors at the door switch and body control module.
3
Door wiring harness
Inspect the wire bundle running through the door hinge area for pinches, cuts, or breaks and repair or replace as needed.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code B1564 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 B1564

What happens after you fix the fault

Once the fault is repaired, B1564 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.