Q: The car shuts off after an hour in the sunlight

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I have problems with my car shutting off after it has been sitting outside when the weather is hot and sunny for more than an hour. I would be able to start it up but it would immediately shut off. I had the motor relay replaced. It didn't help. What could be causing this?

Hello. There may be a problem with the mass airflow sensor on your 2000 Lexus SC400. If the sensor overheats and sends a false reading to the car’s computer, this may result in the engine shutting off. The coolant temperature sensor could also be causing this problem. If the coolant temperature sensor is sending false information to the car’s computer, the fuel levels will be increased or decreased in error depending on the temperature reading of the sensor.

However, in these cases you will normally see a decrease in fuel economy is addition to the engine stalling or shutting off. I would suggest that you have a certified technician, come and complete an inspection to determine why your car starts and then dies and whether or not your car needs a mass airflow sensor replacement.

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