P0549 indicates the Powertrain Control Module (PCM) has detected a high‑voltage condition in the exhaust gas temperature (EGT) sensor circuit for Bank 2 Sensor 1. This typically means the sensor or its wiring is open or has excessive resistance, preventing the PCM from receiving a valid temperature signal. The code is set when the measured voltage exceeds the expected range during the PCM’s self‑test.
The most common cause; an internal open circuit makes the sensor read as high voltage to the PCM.
Open wires, frayed insulation, or corroded terminals can produce the same high‑voltage reading.
While a short to ground usually pulls voltage low, an open in the harness can be misinterpreted as high; proper diagnosis is required.
Inadequate ground can cause the PCM to misread the sensor voltage as abnormally high.
Rare; the PCM can misinterpret the signal, but this is the least likely cause and should be verified after other items are ruled out.
You can drive, but the engine may be in limp‑home mode with reduced power and lower fuel economy; it is advisable to repair the issue promptly to avoid potential turbo or exhaust damage.
In most cases the PCM is not at fault; the problem is usually the sensor or its wiring. PCM replacement should only be considered after the sensor and wiring have been verified as good.
A new sensor resolves the code when the sensor itself is defective, but if the wiring or connectors are damaged the same code can return.
Measuring the sensor’s resistance and checking the circuit for opens/shorts will show whether the fault lies in the sensor or elsewhere.