Lamp Anti-Theft Indicator Circuit Short To Ground
The anti-theft indicator lamp circuit is shorted to ground, preventing the lamp from illuminating properly. Think of it like a light switch where the wire is touching the metal frame instead of completing the intended circuit.
The ECU monitors the anti-theft lamp circuit for proper voltage and resistance. It expects the lamp circuit to draw current when activated, and detects a short to ground when circuit voltage drops to near zero volts without intentional lamp activation. The fault occurs when the ECU cannot establish proper voltage control over the lamp circuit.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Lamp Circuit Voltage | 12V when off, 0-2V when on | Continuous 0V or shorted state regardless of command |
| Circuit Resistance | High resistance (open) when off, low when activated | Continuous low resistance indicating short to ground |
Code B1606 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, B1606 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.