Cellular Phone Handset Not Present
Your vehicle's infotainment system is not detecting a connected phone, similar to a Bluetooth speaker that can't find a device to pair with. The car's network is looking for a phone handset signal but isn't receiving one.
The body control module (BCM) monitors the vehicle's telematics/infotainment network bus for active phone handset presence signals. It expects periodic handshake data from paired or connected devices. When no valid phone signal is detected within the expected timeframe, the fault triggers.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Phone Presence Signal | Active Bluetooth/cellular handset detected on CAN/LIN bus | No handset signal detected for >30 seconds |
| Network Response Time | <2 seconds response from paired device | >5 seconds or timeout |
Code B1874 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, B1874 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.