Ignition Cylinder Sensor Open Circuit
Your vehicle's ignition cylinder sensor has lost electrical connection, like a phone charger that's plugged in but not actually communicating with the device. The engine control module can't detect the ignition key position, preventing proper engine start sequencing.
The ECM monitors the ignition cylinder sensor's voltage signal to detect key position (Off, Acc, On, Start). An open circuit means zero or no signal is reaching the ECM when a signal should be present. The module expects a valid voltage sweep as the key rotates through positions.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Ignition Cylinder Sensor Voltage | 0.5-4.5V (varies by key position) | No signal or below 0.1V consistently |
| Circuit Continuity | Continuous electrical path to ECM | Open circuit / infinite resistance detected |
Code B1492 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, B1492 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.