Illuminated Entry Relay Circuit Failure
The illuminated entry relay—which controls the interior lights when you open a door—isn't working properly, similar to a light switch that's stuck or broken. The vehicle's computer detected an electrical fault in the relay circuit that powers these lights.
The ECU monitors the illuminated entry relay circuit for proper voltage and current draw when the door switches are activated. It expects a specific voltage signal when doors open and detects an open circuit, short to ground, or short to power condition.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Relay Control Voltage | 12V when relay engages; 0V when de-energized | Voltage out of range or stuck at abnormal level |
| Relay Circuit Current | Expected draw within spec | No current or excessive current detected |
Code B1371 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.
Once the fault is repaired, B1371 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.