P24B3: The particulate-sensor heater is checked while regeneration heating is on

P24B3 is particulate-matter sensor heater control circuit/open. Ford’s diesel monitor looks for heater current below 0.2 A while heating is commanded on. The command state is essential: low current with the heater intentionally off is not the same diagnostic event.

Sensor regeneration is the relevant phase

The check runs continuously during particulate-sensor regeneration, with a typical two-second duration. Ford requires the particulate-sensor temperature input to be satisfactory and battery voltage between 11 and 16 V.

This is the sensor’s own regeneration/heating phase. It should not be casually equated with every DPF regeneration event, since the source explicitly names the particulate sensor’s operating state. That distinction helps avoid using the wrong event history as proof of monitor completion.

Compare the neighboring heater code correctly

P24B4 addresses a different observation: unexpected heater voltage when heating is off during sensor measurement. P24B3 instead checks whether the energized heater produces the expected minimum current. The two tests are complementary, not interchangeable.

Useful verification establishes the commanded heater phase, supply conditions, and correct sensor-temperature status before interpreting current evidence. The summary does not locate an open inside the heater versus its wiring, nor provide a safe bench-energizing method. A normal current reading at some other operating phase is not sufficient to certify this check, and the code alone does not prescribe replacement of the complete particulate-sensor assembly.

Source and applicability

This explanation follows Ford’s 2023–2024 diesel OBD summary. Match the vehicle’s engine and calibration before applying these monitor values; a generic code alone does not establish fitment. Ford PDF, page 29.