What does it mean?
P0544 is a generic code trouble code defined as Exhaust Gas Temperature Sensor Circuit Bank 1 Sensor 1 . This code is triggered when the PCM (Powertrain Control Module) fails to receive a plausible signal from the sensor that measures the temperature of exhaust gasses. Exhaust gas temperature is one of the running parameters that PCM in modern cars monitors at all times. There are several reasons for this, with the first having to do with the catalytic converter.
For it to work, the exhaust gas temperature has to be high enough. Otherwise, the catalytic process will not be efficient enough. But if the gases become too hot, they could damage and melt the honeycomb mesh within the converter. In addition, exhaust gas temperature is a crucial parameter in turbocharged engines, which may get damaged if it becomes too hot. The PCM can try to bring the exhaust gas temperature within acceptable limits by adjusting fuel injection or timing.
Or, in the case of turbocharged engines, it will lower the boost. But to do so, it has to know the exhaust gas temperature, and that’s what the EGT sensor is for. Lastly, modern cars and trucks with Diesel engines have a DPF filter. This is short for Diesel Particle Filter, a device installed within the exhaust to catch soot and other particles. With time, the DPF filter gets filled up, which is when the PCM will start the regeneration process.
It does this by adding more fuel during the combustion, which increases the exhaust gas temperature and burns off particles accumulated inside the filter. But to decide when the DPF filter needs to be regenerated, the PCM has to know the exhaust gas temperature before and after it. This is why vehicles with DPF filters have two EGT sensors, one upstream of the filter and the other downstream of it.