P0544 Exhaust Gas Temperature Sensor Circuit Bank 1 Sensor 1

P0544 indicates an exhaust gas temperature sensor circuit issue on Bank 1 Sensor 1. The controller cannot trust the upstream Bank 1 EGT input used for exhaust and catalyst protection.

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 ignore EGT faults on turbo or aftertreatment systems because incorrect temperature data can affect protection strategies.

Symptoms of P0544

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 P0544

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

Compare Bank 1 Sensor 1 EGT data with ambient temperature, exhaust temperature, engine load, DPF or catalyst status, and freeze-frame conditions.
Inspect sensor wiring near exhaust heat, connector condition, reference or bias voltage, ground path, sensor mounting, and soot or impact damage.
Check cold-start plausibility and warm response to determine whether the signal tracks actual exhaust heat.

Related OBD-II codes

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