The coolant temperature sensor plug in a Subaru connects to a sensor that gauges engine temperature. The sensor itself is made of a metal that raises and lowers the resistance between the two terminals of the plug, depending on how hot it gets. The ECU and cluster pick up this resistance value and use a base calibration to equate this input to a specific temperature. It is important to read the temperature beyond just knowing if the engine is overheating, because when the car is started cold, it needs a different fuel mixture compared to when the engine is hot. The correct fuel mixture means a better-running car.
The quickest way to tell you may have an issue with your coolant temperature sensor plug is when the gauge isn't reading properly. Usually, it is due to a bad connector since they are located on top of the engine. Being so close to the hot engine makes the plug brittle and could affect the connection.
Subaru has changed this plug multiple times over the years. It was first two separate plugs, then a three-pin plug, and now it is a two-pin plug. Due to changes with how Subaru communicates (analog vs. digital), the plug has been updated. See below for more specifics about each generation. To purchase, click on one of the connectors needed below!
Generation 1
This plug is seen in 1998 Subaru and older. These cars use two different plugs to read the coolant temp. One is the two pin plug pictured and the second is a single pin plug that can be replaced with a spade terminal.
Car Compatibility:
1992-1997 SVX
1990-1999 Legacy
1990-1999 Outback
1993-1998 Impreza
1998-2002 Forester
Generation 2
This generation of plug combined the functions from the two separate plugs in the previous iteration into a single connector to send output signals to both the ECU and to the cluster.
Compatible Cars:
1999-2007 Impreza
1999-2008 Forester
1999-2004 Legacy
1999-2004 Outback
2001-2006 JDM WRX
2001-2006 JDM STi
2002-2006 Baja
2002-2007 WRX
2004-2007 STI
Generation 3
This type of connector is used in the first generation of CANBUS equipped cars. It has an input for ground and a single output to the ECU. The ECU then sends the signal via CANBUS to the gauge cluster.
Compatible Cars:
2005-2007 Legacy
2005-2007 Legacy GT
2005-2007 Outback
2005-2007 Outback XT
2005-2012 Tribeca
2006-2012 Impreza (Includes Outback Sport)
2006-2013 Forester
2006-2013 Forester XT
2008-2012 STI
2008-2012 WRX
2013 BRZ
Generation 3.5 (Legacy/Outback)
Compatible Cars:
2008-2017 Legacy GT
2008-2017 Legacy Six Cylinder
2008-2017 Outback
2008-2017 Outback XT
2008-2017 Outback Six Cylinder
Generation 4
This generation uses the same input and output style as the last generation, but has changed the connector type.
Compatible Cars:
2013-2020 BRZ
2013-2017 Crosstrek
2013-2019 Outback 6 Cylinder
2013-2019 Legacy 6 Cylinder
2013-2020 STI
2014-2018 Forester
2013-2020 WRX
Generation 5
Compatible Cars:
2022-2025 BRZ
2022-2025 WRX
2018-2025 Crosstrek
2019-2025 Forester
