Exhaust Gas Temperature Sensor Circuit High (Bank 1 Sensor 1)

P0546 means the exhaust gas temperature sensor on bank 1 sensor 1 is reporting a voltage above its valid range. The sensor's wiring is usually the problem before the sensor is: it runs close to the turbo and exhaust, and the insulation cooks, chafes and corrodes, which is why melted or bare wire near the turbo housing is a classic find. Inspect the connector and the full run of the lead for heat damage before ordering a sensor. An exhaust leak near the sensor tip can also skew the reading enough to set the code. A healthy EGT sensor reads on the order of 150 ohms; a reading far below that (under about 50 ohms) indicates a failed sensor - but confirm the spec for your engine, as ranges differ by manufacturer. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.