Aux Blower Sense Switch Circuit Failure
The auxiliary blower motor's feedback sensor isn't communicating properly with the engine control unit, like a light switch that won't signal whether it's on or off. This prevents the ECU from confirming the blower is actually running when commanded.
The ECU monitors the sense switch circuit voltage to confirm the auxiliary blower motor has engaged when commanded. It expects a specific voltage level or signal transition within a set timeframe after sending the blower activation command. If the signal is missing, delayed, or stuck at an abnormal voltage, the ECU logs a circuit failure fault.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Blower Sense Signal Voltage | 0.5–4.5V with proper transition on blower command | No signal change, stuck voltage, or open/short circuit |
| Signal Response Time | Signal detected within 500ms of blower command | No signal or delayed >1 second after command |
Code B2580 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, B2580 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.