Code Definition

B2451 — Aux Heater Fuel Pump Circuit Short to Ground

System: Body  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About B2451

B2451 is a generic (obd-ii standard) body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B2451 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) in the monitored circuit.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

Because B2451 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The auxiliary heater fuel pump is part of the fuel fired cabin and coolant preheating system fitted to many diesel vehicles operating in cold climates, typically a Webasto or Eberspächer style dosing pump that delivers small precise fuel pulses into a combustion chamber where the fuel is burned to warm a coolant heat exchanger. The auxiliary heater control module drives the pump with low duty cycle solenoid pulses and continuously monitors the driver line voltage to confirm correct operation. DTC B2451 is set when the controller detects that the pump driver circuit is shorted to ground, meani...

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