1. Remove the battery cover..
2. Disconnect the negative battery cable..
3. Inspect for resistance and continuity between the seat warmer switch terminals using a tester.

If not as specified, replace the seat warmer switch.
Seat Track Position Sensor Removal/Installation [Two Step Deployment Control
System]
Seat Warmer Switch Removal/InstallationFront passenger occupant classification system
The Subaru Solterra is equipped with an advanced front passenger
occupant classification system that continuously monitors the status of the front
passenger seat. Based on detected conditions, this intelligent system automatically
activates or deactivates specific SRS airbags to optimize safet ...
EGR Valve Inspection [Mzr 2.0, Mzr 2.5]
Resistance Inspection
1. Remove the battery cover..
2. Disconnect the negative battery cable..
3. Disconnect the EGR valve connector.
4. Measure the resistance between the EGR valve terminals.
EGR valve terminal
Resistance inspection (ohm)
...
Cylinder Head Gasket Replacement [Mzr 2.0, Mzr 2.5]
WARNING:
Fuel vapor is hazardous. It can very easily ignite, causing serious injury
and damage. Always keep sparks and flames away from fuel.
Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious
injuries or death and damage. Fuel can also irritate skin ...