P0548: Bank2 low EGT voltage is an electrical threshold, not cold exhaust proof

P0548 is Ford’s low electrical-circuit classification for exhaust-temperature sensor 1 on bank 2. The source pairs it with P0547_16 and gives a sensor-voltage threshold below 0.089 V for five seconds. That is signal evidence; it is not a direct statement that the exhaust gas is colder than expected.

Keep persistence separate from overall registration

The electrical entry window uses battery voltage between 11 and 16 V. The group description lists continuous electrical testing after sensor warm-up and a 30-second malfunction-registration duration, while the low-voltage criterion itself specifies five seconds. These two timing statements should not be collapsed into a promise of one universal warning-lamp delay.

The same page gives an additional inferred-temperature warm-up qualification specifically for the high-voltage check. Its numerical high-test requirements must not be silently treated as P0548’s low-voltage criterion.

Verify the affected signal path

Preserve bank 2 sensor identity, supply voltage, the duration of the low reading and any separate rationality or communication findings. A normal temperature display later does not reconstruct the electrical state during the event.

The source does not localize the low signal to a sensor, wire or controller input. It supplies no connector pin or universal resistance test. The applicable circuit procedure is necessary before a repair decision, with electrical low evidence kept distinct from cold-soak or inferred-temperature plausibility checks.

Source and applicability

Ford 2024–2025 gasoline OBD summary, July 16, 2024 revision; only the described monitor and architecture. Model, engine and calibration fitment are not inferred. The monitor explanation does not identify a failed part or replace the applicable service procedure. Ford PDF, page 6. Ford PDF, page 7.