B1621 – OBD-II DTC

OBD-II DTC B1621 – Wiper Rear Low Limit Input Circuit Short To Battery

DTC B1621 meaning

DTC B1621 refers to a diagnostic trouble code indicating a problem with the rear wiper low limit input circuit. Specifically, it suggests that there is a short circuit to battery voltage in the circuit that monitors the position of the rear wiper. This can prevent the rear wiper from functioning correctly, as the control module is unable to receive accurate position feedback.

DTC B1621 symptoms

Common symptoms associated with DTC B1621 may include:

• Rear wiper not functioning at all
• Rear wiper operating continuously without stopping
• Intermittent operation of the rear wiper
• Dashboard warning lights illuminated

DTC B1621 causes

Several factors can lead to the occurrence of DTC B1621, including:

• Short circuit in the rear wiper low limit input circuit
• Faulty rear wiper motor
• Damaged wiring or connectors in the circuit
• Malfunctioning body control module (BCM)

DTC B1621 seriousness

The seriousness of DTC B1621 can vary based on the vehicle’s usage and the specific symptoms present. While it may not affect the vehicle’s overall drivability, a malfunctioning rear wiper can reduce visibility in adverse weather conditions, posing a safety risk. Therefore, it is advisable to address this issue promptly.

How to diagnose DTC B1621

To diagnose DTC B1621, follow these steps:

1. Use an OBD-II scanner to confirm the presence of DTC B1621.
2. Inspect the rear wiper motor and its wiring for any visible damage or corrosion.
3. Check the connectors for proper seating and signs of wear.
4. Test the rear wiper motor operation by applying direct battery voltage to it.
5. Use a multimeter to check for continuity and shorts in the low limit input circuit.
6. Examine the body control module for any faults or software issues.

How to fix DTC B1621 step-by-step instructions

To fix DTC B1621, follow these steps:

1. Disconnect the vehicle’s battery to ensure safety while working on the electrical system.
2. Inspect and repair any damaged wiring or connectors in the rear wiper circuit.
3. If the rear wiper motor is faulty, replace it with a new or refurbished unit.
4. Reconnect all connectors securely and ensure there are no loose connections.
5. Reconnect the vehicle’s battery.
6. Clear the DTC using an OBD-II scanner and test the rear wiper operation.

How to erase DTC B1621

To erase DTC B1621, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn on the vehicle’s ignition without starting the engine.
3. Navigate to the DTC menu on the scanner.
4. Select the option to clear or erase trouble codes.
5. Confirm the action and wait for the scanner to complete the process.
6. Disconnect the scanner and start the vehicle to ensure the code does not reappear.

Recommended tools for OBD-II diagnostics

Explore our expert picks: The Best OBD2 Scanners for 2025

Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter

Some of the links on this page may be affiliate links, which means we may earn a small commission if you make a purchase. This helps us keep our DTC database up to date and provide valuable content for free. We only recommend products that we have tested and believe to be the best in their class.