Lamp Park Input Circuit Failure
The engine computer can't properly detect the park lamp circuit signal, similar to a light switch that won't send a clear on/off message to the control panel. This prevents the system from knowing when park lights are engaged.
The ECU monitors voltage levels on the park lamp input circuit to detect when park lamps are active. It expects a specific voltage transition between park-on and park-off states. If the signal remains outside acceptable range or fails to transition properly, the fault is triggered.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Park Lamp Input Voltage | 0V (off) or battery voltage (on) with clean transitions | Voltage stuck at intermediate level, open circuit, or short to ground |
| Signal Detection Time | Clear state change within 500ms | No state change detected or excessive noise in signal |
Code B1575 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, B1575 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.