OBD Code B2240: Rear Cargo Door Reset Switch Stuck (Short to Ground)

Q: What does OBD code B2240 mean?

Rear Cargo Door Reset Switch Stuck (Short to Ground). The rear cargo door's reset switch is electrically stuck in the closed position, like a light switch that won't spring back up. The car's computer detects this short circuit and can't tell if the door is actually open or closed.

Q: What are the symptoms of fault code B2240?

Cargo door warning light illuminated on dashboard, Cargo door latch won't engage or disengage properly, Door ajar warning remains active even when door is closed

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What This Actually Means

In plain language — no jargon

The rear cargo door's reset switch is electrically stuck in the closed position, like a light switch that won't spring back up. The car's computer detects this short circuit and can't tell if the door is actually open or closed.

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Symptoms You May Notice

3 known symptoms for this code

Cargo door warning light illuminated on dashboard

Cargo door latch won't engage or disengage properly

Door ajar warning remains active even when door is closed

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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors voltage on the cargo door reset switch circuit, expecting it to toggle between 5V (open) and ground (closed) when the door moves. A short to ground keeps the voltage pinned at 0V continuously, indicating a stuck switch or wiring fault. The ECU sets this code when the signal remains shorted beyond normal switch actuation time.

Voltage & Parameter Thresholds

Parameter	Normal Range	Fault Condition
Reset Switch Voltage	5V open, 0V closed (with normal transitions)	Constant 0V (short to ground) for >2 seconds
Switch Signal Duration	<500ms transition time	>2000ms continuous short

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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex

1

Cargo door reset switch connector

Inspect and reseat the electrical connector at the door latch mechanism; corrosion or loose pins often cause false shorts.

2

Cargo door reset switch

Replace the switch assembly if connector is clean but voltage remains shorted; switches commonly fail in the closed position.

3

Cargo door wiring harness

Check for pinched or damaged wires between the door and frame; repair or replace any sections with exposed insulation.

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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code B2240 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 B2240

What happens after you fix the fault

Once the fault is repaired, B2240 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.