Aux Heater Fuel Pump Circuit Short to Ground
The auxiliary heater's fuel pump circuit is shorted to ground, meaning electricity is taking an unintended shortcut instead of powering the pump normally. Think of it like water flowing out of a hole in a pipe instead of reaching the destination.
The ECU monitors the aux heater fuel pump circuit for proper resistance and voltage draw. When the circuit shorts to ground, the ECU detects abnormally low or zero resistance, indicating a direct path to ground instead of normal pump operation. The control module expects a specific voltage drop across the pump during operation.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Circuit Resistance | 50-500 ohms when pump inactive | Less than 5 ohms (short to ground) |
| Circuit Voltage | 12V supply with normal load draw | 0V or continuous ground path detected |
Code B2451 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, B2451 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.