What does the P0073 fault code in the LaCrosse mean?
3 Answers
LaCrosse P0073 fault code indicates a high circuit condition in the ambient air temperature sensor. Introduction to automotive fault codes: Automotive fault codes are error codes generated by the vehicle's ECU (Engine Control Unit) after analyzing malfunctions. Generally, these codes are caused by sensor failures or poor sensor performance, but some mechanical faults cannot be detected by the ECU. Function of automotive fault codes: During vehicle development, there is an increasing trend toward intelligence, mechanization, and automated control. This requires control units to autonomously assess the status of surrounding components and the environment as much as possible and quickly execute corresponding control functions. Control is a comprehensive decision-making process, and fault codes are essential conditions in the control logic, used to determine whether certain functions meet the control criteria.
I've helped a friend deal with the P0073 trouble code on a Buick LaCrosse before. It's actually an issue with the intake air temperature sensor. This component is installed on the intake pipe and specifically monitors the temperature of air entering the engine. When it throws a code, it's usually because either the wiring got chewed by rodents, the connector corroded from water exposure, or the sensor itself got fouled by oil - that last one's pretty common. When faulty, the engine control module starts guessing temperatures, which can lead to excessive fuel injection and skyrocketing fuel consumption in summer, or rough cold starts like gasping for air in winter. Last time I worked on my friend's car, I noticed an interesting detail: carbon buildup blocking the sensor's port can also trigger false readings. A couple sprays of carb cleaner fixed it - a trick many repair shops might not tell you about.
Last time I read the diagnostic trouble code P0073, the owner was complaining about lack of power during acceleration. This code specifically indicates an excessively high signal voltage from the intake air temperature sensor, which is essentially the sensor telling the ECU 'the air is hot enough to fry eggs'. The key areas to inspect are three wires: the 5V reference voltage, signal wire, and ground wire. I've encountered cases where a loose connector was the issue - simply reseating it cleared the fault code. If the sensor is bathed in oil vapor (especially common in turbocharged vehicles), the probe can get coated with sludge. I recommend first cleaning the mounting hole, then measuring resistance - it should read about 2.5 kΩ at 20°C and drop to around 300 Ω at 80°C. Don't forget to check if the wiring harness is too close to the exhaust pipe, as prolonged heat exposure can make the insulation brittle.
