Spring 2005 Forward to a Friend







Future governmental regulations may call for new vehicles to have tire pressure monitoring systems (TPMS) to warn of low tire pressure. As one of its safety initiatives, Subaru already installs TPMS on these 2005 Outback models:

Sedan 3.0 R
Wagon 3.0 R L.L.Bean®
Wagon 3.0 R VDC Limited

Other models will follow.

What TPMS Does

TPMS is intended to alert the driver if tire pressure in one or more tires falls below a preset value. A drop in tire pressure could result from:

A puncture caused by a nail or other foreign object
A poor seal between the tire and wheel
The need for routine tire maintenance
Changes in ambient temperature

Subaru TPMS is designed to illuminate a warning light if air pressure in any tire drops between 26 and 27 pounds per square inch (psi). When all tires are above a minimum pressure of 29 psi, the warning light is off.



The low and minimum pressure levels used by the Subaru TPMS are lower than the recommended cold-tire pressure for original-equipment tires. When not towing, recommended pressures are 32 psi front and 30 psi rear. Subaru lists recommended tire pressures in the Owner’s Manual (2005 Legacy – Maintenance and Service section, page 50) and on placards fixed to driver’s-side door pillars.
 
TPMS Components


Major Subaru TPMS components include:

Integrated valve stem and air-pressure sensor/ transmitter assembly with battery – each wheel
Receiver – under the driver’s seat
TPMS warning light – part of the instrument panel


How TPMS Works

The wheels’ air-pressure sensor/transmitter assemblies transmit individual air-pressure levels via radio signal to the receiver/control unit. Roll switches in the assemblies turn on the sensors when vehicle speed reaches between seven and 20 mph.

Transmitter data include detected air pressure, ID code and a code indicating the transmitter’s current mode. Each assembly’s sensor takes measurements every 30 seconds, which are transmitted every 60 seconds. After the vehicle has stopped for 15 minutes, the sensors enter sleep mode to conserve their batteries. They have life expectancies of 10 years or 100,000 miles.

The receiver/control unit collects data from the sensor/transmitter assemblies via a built-in antenna. If air pressure drops between 26 and 27 psi in one or more of the tires, the unit illuminates the warning light in the instrument panel (the system design does not indicate which tire is low).

TPMS – Important Safety Technology

Subaru equips vehicles with TPMS to improve safety. By warning of a tire’s air-pressure loss, TPMS helps drivers avoid accidents. An added benefit is the reduced wear and tear to a vehicle’s power train and chassis, potentially improving durability and lowering the cost of ownership.

(Don’t forget to check the air pressure in your tires at least once a month – especially after drastic fluctuations in ambient temperature. An investment in a quality tire gauge can save you money and improve safety!)




The low and minimum pressure levels used by the Subaru TPMS are lower than the recommended cold-tire pressure for original-equipment tires. When not towing, recommended pressures are 32 psi front and 30 psi rear. Subaru lists recommended tire pressures in the Owner’s Manual (2005 Legacy – Maintenance and Service section, page 50) and on placards fixed to driver’s-side door pillars.

For the 2005 Outback, Subaru specifies tire pressures set with cold tires (60° F). When tires are warmer or cooler than 60° F, pressure needs to be adjusted. Compensate for large swings to colder temperatures according to the following table.

If you drive out of your heated garage on a cold day and the TPMS warning light comes on, stop to check if the tires are low. Chances are you need air due to the swing to colder temperatures.

If you’ve been driving for a while (more than 20 minutes) and the light illuminates, you probably have a problem caused by a tire going flat.

  front rear
Garage temperature Recommended pressure (psi)
60° F 32 30
Outside temperature Adjusted pressure (psi)
30° F 35 30
10° F 37 35
-10° F 39 37
See more information in the Maintenance and Service portion of the Owner’s Manual.