2015-2018 Subaru Forester TPMS & Keyless Entry Module: Water Damage, Failures, and Replacement
This guide explains why a faulty TPMS module can also disable your keyless entry and how to diagnose and replace it correctly.
- This module controls both the TPMS and Keyless Entry; failure often affects both systems at once.
- The most common cause of failure is water intrusion from clogged moonroof drains leaking into the trunk.
- A replacement module MUST be programmed by a shop with a TPMS scan tool; it is not plug-and-play.
- Ensure you buy the correct part number: 28201SG060 for 2.5L engines and 28201SG010 for 2.0L Turbo models.
Known Issues & Common Failure Modes
The single most common cause of failure for the TPMS & Keyless Entry Module in the 2015-2018 Forester is water intrusion. This is a significant design vulnerability that owners and technicians should be aware of.
Water Damage from Moonroof Drains
The module is located in the rear of the vehicle, typically in the trunk area on the passenger side, behind the trim panels. Unfortunately, this location is very close to the drain tubes for the factory moonroof. Over time, these rubber drain tubes can become clogged with dirt, leaves, and other debris. When the drains are blocked, rainwater that would normally exit under the vehicle backs up and overflows, often leaking directly onto the TPMS module and its wiring harness.
The water causes corrosion on the circuit board and connector pins, leading to short circuits and eventual failure of the module. Early signs of this issue might be intermittent problems with the key fob or TPMS light, which become permanent as the corrosion worsens.
Pro Tip: During diagnosis, always pull back the trunk liner to physically inspect the module for signs of water damage, such as white or greenish residue on the casing, rust on the mounting bracket, or corrosion on the electrical connector pins. If the area is damp or smells musty, clogged moonroof drains are the likely culprit.
Symptoms of a Failing TPMS & Keyless Entry Module
Because this module controls two separate systems, its failure can cause a confusing set of symptoms. Look for a combination of the following:
- TPMS Warning Light: The TPMS light on the instrument cluster may illuminate and stay on, or it may flash for about a minute before staying on solid. This happens even when all tires are properly inflated.
- Keyless Entry Failure: The lock, unlock, and panic buttons on your key fobs suddenly stop working. You will have to use the physical key to lock and unlock the doors. The car will still start and run, as the immobilizer chip in the key is part of a different system.
- Inoperative Trunk Light: In some cases, the trunk's interior light may also stop working, as it is linked to the same control unit.
The most telling sign of a failed module is when the TPMS light appears at the same time the key fobs stop working.
Compatibility: 2.5L vs. 2.0L Turbo Engines
Warning: The TPMS module is engine-specific. The part number for the naturally aspirated 2.5L engine is different from the one used in the 2.0L turbo (XT) models.
- 2.5L Engine Models: Use part number 28201SG060.
- 2.0L Turbo (XT) Models: Use part number 28201SG010.
These modules are not interchangeable. Installing the wrong module will result in it not functioning. Always match the part number exactly or verify compatibility with the vehicle's VIN.
Programming and Calibration Requirements
A replacement TPMS module must be programmed to the vehicle after installation. This is not a plug-and-play part. The process involves registering the unique ID codes of your vehicle's existing tire pressure sensors to the new module.
This procedure cannot be done by the vehicle owner without special equipment. It requires a compatible OBD-II diagnostic scan tool with TPMS functionality, such as those made by Autel or ATEQ. Therefore, after physically replacing the module, the vehicle must be taken to a Subaru dealership or a well-equipped independent auto repair or tire shop to have the programming completed. Without this step, the TPMS light will not turn off and the system will not function.
Buying a Used TPMS & Keyless Entry Module
A used OEM module is a cost-effective alternative to a new part, especially since aftermarket options are not common. However, given the high failure rate from water damage, careful inspection is critical.
- Verify the Part Number: Double-check that you are buying the correct part number for your Forester's engine (28201SG060 for 2.5L or 28201SG010 for 2.0L).
- Inspect for Corrosion: Closely examine the photos of the used part. Look for any white, green, or blueish powder-like residue on the plastic casing or, more importantly, inside the electrical connector port. Do not buy any module that shows signs of water exposure.
- Check the Casing: Ensure the plastic housing is not cracked or broken. Ask the seller for photos of the connector pins to ensure they are straight and clean.
- Source from a Dry Climate: If possible, purchase a module from a vehicle that was operated in a dry, arid climate to reduce the risk of prior water exposure.
Cost Comparison
Prices can vary by location and supplier. The following are estimates to help you understand the potential costs.
| Part Type | Estimated Cost |
|---|---|
| New OEM (Dealer) | $180 - $220 |
| New OEM (Online) | $125 - $150 |
| Used OEM | $50 - $100 |
| Shop Labor (Replacement & Programming) | $100 - $200 |
Frequently Asked Questions (FAQ)
Why did my key fob stop working when the TPMS light came on?
On the 2015-2018 Forester, Subaru integrated the receiver for the keyless entry system into the same electronic module that controls the Tire Pressure Monitoring System. When this module fails (often due to water damage), both systems stop working simultaneously.
Can I replace and program this module myself?
You can physically replace the module yourself to save on labor costs, as it is typically held in by a few bolts and has one electrical connector. However, the final, mandatory step is programming the new module to recognize your car's tire sensors. This requires a professional-grade OBD-II scan tool, so a trip to a shop is necessary to complete the job.
Where is the TPMS module located on my 2016 Forester?
The module is located in the rear of the vehicle, behind the interior trim panels in the cargo area. It is most commonly found on the passenger side, mounted vertically near the wheel well.
Is this the same as an "Active Suspension Control Module"?
No. The 2015-2018 Subaru Forester is not equipped with an active suspension system. The correct name for this part is the TPMS Control Module. The "Active Suspension" name is a mislabeling that sometimes occurs in generic parts catalogs.
Technical Specifications
OEM Part Numbers: 28201SG060 28201SG010
Also known as 'Unit TPMS Assembly 18N'. Controls both TPMS and Keyless Entry functions.
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Subaru Forester:
- 🛍️ Shop This Part
- Known Issues & Common Failure Modes
- Water Damage from Moonroof Drains
- Symptoms of a Failing TPMS & Keyless Entry Module
- Compatibility: 2.5L vs. 2.0L Turbo Engines
- Programming and Calibration Requirements
- Buying a Used TPMS & Keyless Entry Module
- Cost Comparison
- Frequently Asked Questions (FAQ)
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