P0548 Exhaust Gas Temperature Sensor Circuit Low Bank 2 Sensor 1

P0548 points to a low signal from Exhaust Gas Temperature Sensor Bank 2 Sensor 1. The upstream Bank 2 EGT reading is below the expected range.

Code details

Generic OBD-II · P0

System: Speed / Idle
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace exhaust hardware before testing the low EGT signal and wiring near Bank 2.

Symptoms of P0548

Unstable, high, or low idle, or stalling.
Erratic speedometer, cruise-control, or shift behaviour.
Check-engine light with a hesitation or surge.

Common causes of P0548

A dirty throttle body, idle-control valve, or throttle-position sensor.
A failing vehicle-speed or wheel-speed sensor, or its wiring.
Vacuum leaks or a related sensor forcing the idle/speed strategy.

Useful checks before replacing parts

Check Bank 2 Sensor 1 EGT signal voltage, bias or reference circuit, ground, cold-start reading, engine load, and freeze-frame data.
Inspect for short-to-ground faults, open bias circuits, exhaust-heat damaged wiring, connector corrosion, and failed sensor elements.
Compare Bank 2 readings to ambient and Bank 1 behavior to determine whether the fault is electrical or thermal.

Related OBD-II codes

These nearby speed / idle entries can help compare wording and pin down the fault area.