Parts for your 1999 Subaru Forester-Map sensor

1999 Subaru Forester MAP sensor — what it does and how to look after it

Yes, the 1999 Subaru Forester is fitted with a MAP (Manifold Absolute Pressure) sensor. Subaru’s factory service information for the SF-series Forester (1998–2002) describes a MAP sensor input to the ECM and provides diagnostics for faults such as P0105–P0108, while Subaru parts catalogues list a “pressure/MAP sensor” for 1999 Forester variants. On turbocharged JDM models it’s also used for boost measurement. Even on many naturally aspirated models that still use a MAF, Subaru specifies a separate MAP/pressure sensor for load, barometric and EGR-related control. References: Subaru Forester (SF) Factory Service Manual, Engine Control (EC) diagnostics for MAP sensor, Subaru genuine parts listings for 1999 Forester pressure/MAP sensor.

On this Forester, the MAP sensor measures absolute pressure in the intake manifold so the ECU can work out engine load. That affects fuel delivery, ignition timing and idle control, and it also helps the car cope with altitude changes across NZ and Australia. Turbocharged versions rely on the sensor for boost control and engine protection.

It’s a solid-state part, so there’s no regular service interval, but a few simple checks during routine servicing help it live a long life:

• Inspect the vacuum hose (if fitted) for splits, softness or oil contamination, and replace if perished.
• Check the connector for green corrosion, loose pins or broken locks, clean with proper electrical contact cleaner only.
• Avoid spraying throttle or intake cleaners upstream if they can pool and be drawn into the sensor.

Typical symptoms of a crook MAP sensor include hard starting, rough idle, flat spots, poor fuel economy and a check-engine light with codes like P0105–P0108. Before blaming the sensor, rule out vacuum leaks and cracked hoses — they’ll skew readings the same way.

Replacement is straightforward: disconnect the battery, unplug the connector, remove the retaining fastener(s), and, if there’s a vacuum hose, swap it with a new one. Fit the new sensor, reconnect, clear any codes and let the ECU relearn with a gentle drive. Use only quality parts that match the original spec — the ECU expects a precise voltage-to-pressure curve.

Treat the MAP sensor kindly and the Forester will reward with smooth drivability, decent litres per 100 km and reliable cold and hot starts under the bonnet’s everyday conditions.

Popular questions about the 1999 Subaru Forester MAP sensor

Where is the MAP sensor located on a 1999 Forester?
It’s typically mounted on or near the intake manifold. Some variants have it bolted to the manifold with a short vacuum passage, others use a small hose from the manifold to a remote-mounted sensor on a bracket near the throttle body or firewall.

Can a MAP sensor be cleaned, or should it be replaced?
If contamination is light, carefully cleaning the port and checking the connector can restore proper readings. Avoid harsh solvents. If the diaphragm or electronics are faulty (codes return, data is erratic), replacement is the go.

What fault codes point to a bad MAP sensor?
Common DTCs include P0105 (MAP circuit), P0106 (range/performance), P0107 (low input) and P0108 (high input). Always verify supply voltage, ground, signal voltage and vacuum integrity before fitting a new sensor.