P0545 Exhaust Gas Temperature Sensor Circuit Low Bank 1 Sensor 1

P0545 points to a low signal from Exhaust Gas Temperature Sensor Bank 1 Sensor 1. The EGT feedback is below the expected electrical or thermal 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 aftertreatment components until the low EGT signal circuit is verified.

Symptoms of P0545

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 P0545

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 1 Sensor 1 EGT signal voltage, reference or bias circuit, ground, cold-start temperature, engine load, and freeze-frame data.
Inspect for short-to-ground faults, open supply or bias circuits, damaged wiring insulation near exhaust heat, connector corrosion, and failed sensor elements.
Compare the reading to ambient temperature before startup and to exhaust heat during operation to separate circuit faults from true low temperature.

Related OBD-II codes

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