What does it mean?
This is a generic powertrain code, meaning it covers all makes/models from 1996 onward. However, specific troubleshooting steps vary by vehicle.
This Diagnostic Trouble Code (DTC) P0544 refers to the condition of the EGT (Exhaust Gas Temperature) sensor located in the “upstream” pipe in front of the catalytic converter. Its sole purpose is to protect the converter from damage due to excessive heat.
Code P0544 indicates a general malfunction detected in the EGR temperature sensor circuit on Bank 1, Sensor #1. This DTC P0544 refers to Bank #1 (which is the engine side containing cylinder #1). Related codes are P0545 (low circuit) and P0546 (high circuit).
An EGT sensor is found on most recent model gasoline or diesel engines. It’s essentially a thermistor that converts exhaust temperature into a voltage signal for the computer. It receives a 5-volt signal from the computer via one wire while the second wire is grounded.
The higher the exhaust temperature, the lower the resistance to ground results in higher voltage – conversely, the lower the temperature, the higher the resistance results in lower voltage. If the engine detects low voltage, the computer will adjust engine timing or fuel ratio to maintain temperature within acceptable ranges in the converter.
In a diesel, the EGT is used to determine the timing of DPF (Diesel Particulate Filter) regeneration based on temperature increase.
If a catless pipe was installed with the catalytic converter removed, there’s normally no provision for the EGT, or if present, it won’t function properly without backpressure. This will set the code.
Symptoms
The check engine light will illuminate and the computer will have set code P0544. No other symptoms will be readily noticeable.
Potential Causes
Causes of this DTC may include:
- Check for loose or corroded connectors or terminals, which is often the case
- Broken wires or missing insulation can cause a direct short to ground
The sensor may have failed - A catback exhaust system installed without EGT provisions
- Computer failure is possible but unlikely
Repair Procedures
Lift the vehicle and locate the sensor. For this code, it refers to the sensor on Bank 1, which is the engine side containing cylinder #1. It’s located between the exhaust manifold and the converter, or in the case of a diesel, before the Diesel Particulate Filter (DPF). It looks different from oxygen sensors in that it’s only a two-wire plug. A vehicle with a turbo will have the sensor near the turbo’s exhaust inlet.
Check connectors for any abnormalities such as corrosion or loose terminals. Follow the pigtail to its connector and check it as well.
Look for signs of missing insulation or bare wires that could be shorted to ground.
Disconnect the upstream connector and remove the EGT sensor. Check resistance with an ohmmeter. Probe both terminals of the connector. A good EGT will have about 150 ohms. If there’s very little resistance – below 50 ohms, replace the sensor.
Use a hairdryer or heat gun and heat the sensor while watching the ohmmeter. Resistance should decrease when the sensor is heated and increase when cooling. Otherwise, replace it.
If everything was good at this point, turn the key on and measure voltage on the engine side of the pigtail. There should be 5 volts at the connector. If not, replace the computer.
Another reason this code might be set is if the catalytic converter was replaced in favor of a catback system. In most states, this is an illegal procedure subject to heavy fines if caught. It’s advisable to check local and national laws regarding removal of this system as it allows uncontrolled emissions into the atmosphere. It may work, but it’s everyone’s responsibility to do our part to keep our atmosphere clean for future generations.
Until this is repaired, the code can be reset by purchasing a 2.2 ohm resistor for pocket change at any electronics store. Simply discard the EGT sensor and plug the resistor into the engine-side electrical connector. Wrap it with tape and the computer will be convinced the EGT is functioning properly.