Quick Answer

Install a cold air intake on your 2015-2021 Subaru WRX by disconnecting the battery, removing the factory airbox, fitting the new intake with its heat shield, and rechecking all clamps. A tune or calibration is strongly recommended after installation to safely realize the performance gains.

Why the Heat Shield Matters

The 2015-2021 WRX engine bay runs hot, and the factory intake is designed to pull air from the fender. An aftermarket intake without a heat shield can suck in hot under-hood air, reducing power and increasing intake air temperatures. The PLM Cold Air Intake with Heat Shield addresses this by including a shield that blocks radiant engine heat, helping keep the incoming air cooler and denser for better combustion.

A proper heat shield also helps maintain consistent performance during spirited driving or track sessions, where heat soak can rob power. If you choose an intake without a shield, consider fabricating or purchasing one separately to avoid losing the benefits of increased airflow.

Tuning Considerations for the WRX

The 2015-2021 WRX uses a mass airflow sensor that can be affected by changes to intake pipe diameter and airflow characteristics. Installing a cold air intake without recalibration may cause the engine to run lean or rich, triggering a check engine light. Many aftermarket intakes for the WRX require an accessport or professional tune to adjust the fuel trims and ensure safe operation.

If you are not ready to tune, consider an intake that is specifically designed to work with the stock calibration, or plan to budget for a tune as part of the upgrade. The PLM intake is engineered for performance, but like most aftermarket intakes, it is best paired with a calibration to unlock its full potential.

Installation Steps

  1. Disconnect the Battery: Turn off the engine and disconnect the negative battery terminal. This resets the ECU and prevents any electrical shorts while you work near the engine bay. Wait at least 10 minutes after disconnecting to allow the ECU to fully reset.
  2. Remove the Factory Airbox: Unclip the mass airflow sensor connector, loosen the hose clamps on the intake tube, and lift the airbox out. Set aside the factory parts, but keep the MAF sensor and its harness intact. Do not force the airbox out; check for hidden clips or bolts to avoid breaking the plastic.
  3. Install the Heat Shield: Position the heat shield in the engine bay, aligning its mounting points with the existing holes. Secure it with the supplied hardware, but do not fully tighten until the intake is in place. Make sure the shield does not rub against the turbo or other hot components.
  4. Mount the New Intake Pipe: Attach the intake pipe to the turbo inlet, then connect the MAF sensor housing to the filter side. Use the supplied couplers and clamps, and hand-tighten them temporarily. Ensure the MAF sensor is oriented correctly; arrow or flow direction is usually indicated on the housing.
  5. Connect the MAF Sensor and Hoses: Reconnect the MAF sensor electrical connector and any crankcase ventilation hoses that were disconnected. Double-check that all fittings are snug and no vacuum lines are kinked. A loose MAF connection can cause a rough idle or stall.
  6. Tighten All Clamps and Final Check: Tighten all clamps to the manufacturer's specification, ensuring the intake is secure and does not move when you pull on it. Inspect for any loose bolts or tools left in the bay. Re-torque the clamps after a short drive, as they can loosen as the rubber couplers settle.
  7. Reconnect Battery and Test: Reconnect the negative battery terminal, start the engine, and let it idle for a few minutes. Listen for unusual sounds and check for any check engine light. If the check engine light appears, scan for codes; a tune may be required to clear MAF-related codes.

  • PLM Cold Air Intake with Heat Shield Fits Subaru WRX 2015 - 2021: The PLM Cold Air Intake with Heat Shield is engineered for maximum performance and enhances airflow to the turbocharged engine, resulting in noticeable horsepower and torque gains. This intake is designed specifically for the 2015-2021 WRX, ensuring a proper fit and the airflow improvements you expect from an aftermarket upgrade.

    PLM Cold Air Intake with Heat Shield Fits Subaru WRX 2015 - 2021

    PLM Cold Air Intake with Heat Shield Fits Subaru WRX 2015 - 2021