B1571 – OBD-II DTC

OBD-II DTC B1571 – Door Ajar LR Circuit Failure

DTC B1571 meaning

DTC B1571 refers to a “Door Ajar LR Circuit Failure,” indicating a malfunction in the left rear door’s ajar switch circuit. This diagnostic trouble code (DTC) is part of the On-Board Diagnostics II (OBD-II) system, which monitors various vehicle components for faults. The left rear door’s ajar switch is responsible for signaling whether the door is open or closed, and a failure in this circuit can lead to incorrect readings or warnings on the vehicle’s dashboard.

DTC B1571 symptoms

Common symptoms associated with DTC B1571 may include:

• Dashboard warning light indicating a door ajar
• Interior lights remaining on when the vehicle is off
• Inconsistent door lock operation
• Audible alerts or chimes when the vehicle is in motion

DTC B1571 causes

Several factors can lead to the occurrence of DTC B1571, including:

• Faulty left rear door ajar switch
• Wiring issues, such as shorts or open circuits
• Corrosion or damage in the connector terminals
• Faulty Body Control Module (BCM) that processes the door signals

DTC B1571 seriousness

The seriousness of DTC B1571 can vary. While it may not affect the vehicle’s drivability, it can lead to safety concerns, such as:

• Interior lights draining the battery
• Inability to secure the vehicle properly
• Potential for false alerts that may distract the driver

Addressing this issue promptly is recommended to ensure proper vehicle operation and safety.

How to diagnose DTC B1571

To diagnose DTC B1571, follow these steps:

1. Use an OBD-II scanner to confirm the presence of DTC B1571.
2. Inspect the left rear door ajar switch for physical damage or wear.
3. Check the wiring and connectors for signs of corrosion or damage.
4. Test the continuity of the circuit using a multimeter.
5. Examine the Body Control Module (BCM) for faults or software issues.

How to fix DTC B1571 step-by-step instructions

To fix DTC B1571, follow these step-by-step instructions:

1. Clear the DTC using an OBD-II scanner.
2. Inspect and replace the left rear door ajar switch if faulty.
3. Repair or replace any damaged wiring or connectors.
4. Test the circuit again to ensure proper function.
5. If necessary, reprogram or replace the Body Control Module (BCM).
6. Recheck for DTCs after repairs to confirm the issue is resolved.

How to erase DTC B1571

To erase DTC B1571, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn the ignition key to the “On” position without starting the engine.
3. Navigate to the “Erase Codes” or “Clear DTCs” option on the scanner.
4. Confirm the action to clear the trouble codes.
5. Disconnect the scanner and start the vehicle to ensure the code does not return.

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