NGK Direct Fit (B1S2) Oxygen Sensor Subaru WRX 15-21 / Forester XT 14- – Import Image Racing
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NGK Direct Fit (B1S2) Oxygen Sensor Subaru WRX 15-21 / Forester XT 14-18 | 24478
NGK Direct Fit (B1S2) Oxygen Sensor Subaru WRX 15-21 / Forester XT 14-18 | 24478
NGK Direct Fit (B1S2) Oxygen Sensor Subaru WRX 15-21 / Forester XT 14-18 | 24478
NGK Direct Fit (B1S2) Oxygen Sensor Subaru WRX 15-21 / Forester XT 14-18 | 24478

NGK Direct Fit (B1S2) Oxygen Sensor Subaru WRX 15-21 / Forester XT 14-18 | 24478

SKU: ngk24478
Availability: 3 In Stock
Product Type: Engine Management Sensors
$125.00
$140.02
$125.00
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Product Fitment:

2015-2021 Subaru WRX

2014-2018 Subaru Forester XT

The NTK 24478 Oxygen Sensor is engineered to deliver OEM-level fitment, function, and reliability. Designed as a direct replacement for factory downstream (post-catalytic converter) sensors, it helps your vehicle maintain an ideal air-fuel ratio, optimize fuel efficiency, and reduce emissions.

Key Features & Benefits

  • OE-Identical Design: Matches the original equipment sensor in fit, function, and performance for reliable replacement.

  • Premium Materials: Features a precision ceramic sensing element with dual-platinum electrodes for fast response and long life.

  • Heated 4-Wire Construction: Provides rapid sensor warm-up and consistent signal output for precise ECU feedback.

  • Water-Resistant Connector: Includes an OE-style sealed plug for protection against moisture and corrosion.

Specifications

  • Thread Diameter: M18 × 1.5 mm

  • Wrench Size / Hex: 22 mm (7/8″)

  • Wire Length: 9.5″ (241 mm)

  • Sensor Type: Heated, 4-wire

  • Position: Downstream (post-catalytic converter)

Applications

The NTK 24478 is ideal for replacing aging or faulty downstream oxygen sensors that trigger check engine lights, reduce catalytic efficiency, or cause poor fuel economy. It fits many Subaru models and other compatible vehicles requiring this part specification.

Why Replace It?

Oxygen sensors naturally degrade over time due to heat and contaminants. A failing sensor can cause:

  • Poor fuel mileage

  • Increased emissions

  • Engine hesitation or rough idle

  • Check Engine Light (CEL) codes such as P0136, P0137, or P0138

Installing a new NTK 24478 ensures accurate air-fuel ratio feedback to your ECU, restoring optimal combustion and emission control performance.

Installation Tips

  • Verify compatibility with your vehicle’s VIN or OEM part number.

  • Apply a small amount of anti-seize to threads (avoid the sensor tip).

  • Inspect and clean connector terminals before installation.

  • Clear diagnostic trouble codes (DTCs) after replacement to reset ECU adaptations.

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