B1378 – OBD-II DTC

OBD-II DTC B1378 – Oil Change Lamp Circuit Short To Ground

DTC B1378 meaning

DTC B1378 refers to a diagnostic trouble code indicating a short circuit to ground in the oil change lamp circuit. This code is part of the On-Board Diagnostics II (OBD-II) system, which monitors various vehicle systems for faults. The oil change lamp is designed to alert the driver when an oil change is due, and a short to ground can prevent this warning from functioning properly.

DTC B1378 symptoms

Common symptoms associated with DTC B1378 may include:

• Oil change lamp not illuminating when it should
• Oil change lamp remaining illuminated continuously
• Possible engine performance issues due to lack of maintenance reminders
• Other dashboard warning lights may also be affected

DTC B1378 causes

Several factors can lead to the occurrence of DTC B1378, including:

• Wiring issues such as frayed or damaged wires
• Corroded connectors in the oil change lamp circuit
• Faulty oil change lamp or bulb
• Malfunctioning engine control module (ECM)
• Improper installation of aftermarket components

DTC B1378 seriousness

DTC B1378 is considered a moderate issue. While it does not typically affect the vehicle’s drivability, it can lead to missed maintenance reminders, potentially resulting in engine damage if oil changes are neglected. Addressing this code promptly is advisable to ensure proper vehicle maintenance.

How to diagnose DTC B1378

To diagnose DTC B1378, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the B1378 code.
2. Inspect the wiring and connectors associated with the oil change lamp circuit for damage or corrosion.
3. Check the oil change lamp or bulb for proper operation.
4. Test the continuity of the circuit to ensure there are no shorts to ground.
5. Examine the ECM for any faults or software issues that may affect the oil change lamp operation.

How to fix DTC B1378 step-by-step instructions

To fix DTC B1378, follow these steps:

1. Repair or replace any damaged wiring or connectors found during diagnosis.
2. Replace the oil change lamp or bulb if it is faulty.
3. Ensure all connections are secure and free from corrosion.
4. If necessary, reprogram or replace the ECM to resolve any software issues.
5. Clear the DTC using an OBD-II scanner and test the system to ensure the oil change lamp operates correctly.

How to erase DTC B1378

To erase DTC B1378, 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. Access the trouble codes menu on the scanner.
4. Select the option to clear or erase codes.
5. Confirm the action and wait for the scanner to indicate that the codes have been cleared.
6. Disconnect the scanner and start the vehicle to verify that the DTC 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.