Does the 2009 Subaru WRX have a TPM (Tire Pressure Monitor) installed? When I recently changed my tires the installer said it did not have any monitor. That made me wonder, how does the low tire pressure indicator light on my dashboard work?

1 Answer 1


They use a rotation sensor, or rotation speed sensor. When the tire looses air it's circumference becomes smaller, so the sensor's signal changes and sets off the light.

Added: See this site for a full explanation of Subaru's TPM


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