Oxygen Sensor-Engineered Bosch 15427

Bosch 15427 Oxygen (O2) Sensor — Upstream / Pre-Cat — Direct Fit for Mazda 6 2.3L & Mazda Millenia 2.5LCore SpecificationsBrandBOSCHPart Number15427Sensor TypeNarrow-Band HeatedWire Quantity4ThreadM18 x 1.5Hex Size22mmConnectorMale, RectangleHarness Length22.1 inOverall Length25.8 inFitment TypeDirect FitVehicle 62.3L L4UpstreamBank 1 Sensor 1MAZDA2001-2002Millenia2.5L V6Upstream Right-Critical Fitment NoticePLEASE VERIFY BEFORE PURCHASING:

• Position: Upstream (Pre-Cat / Before Catalytic Converter).
• Mazda 6 2.3L: Fits Bank 1 Sensor 1 (Upstream). The downstream counterpart is Bosch 15426.
• Millenia 2.5L: Fits Upstream Right.
• Connector Verification: Features a male rectangular connector. Please visually compare with your existing sensor plug before ordering.
• Incompatible Models: DOES NOT fit Mazda 6 3.0L V6 (requires Bosch 15429/15430 family) or Millenia 2.3L V6 Supercharged (requires Bosch 13574/13576 family).

Key Features & OE Quality

• OE Quality Benchmark: Manufactured by Bosch, the original inventor of the automotive oxygen sensor, guaranteeing top-tier reliability and performance.
• Direct Fit: Comes equipped with OEM-matching connectors and harnesses for true plug-and-play installation—no wire cutting or splicing required.
• Enhanced Durability: Features a double laser-welded stainless steel body that protects the internal ceramic sensing element from contamination and corrosion.
• Pre-Applied Anti-Seize: Threads come pre-coated with anti-seize compound directly out of the box to prevent thread galling and ensure smooth installation.

OE & Cross Reference Numbers

OEM Numbers: KL1D188619U, L32118861B

ApplicationBrandPart NumberPositionMazda 6 2.3L (2003-2005)BOSCH15427Upstream (This (Bank 1 Sensor 1)DELPHIES20386UpstreamMillenia 2.5L (2001-2002)BOSCH15427Upstream Right (This Item)DENSO2344121Upstream RightNTK22119Upstream FrontDiagnostic CEL Codes & Installation Guide

Check Engine Light (CEL): Replacing a failing upstream sensor commonly resolves the following fault codes:

• P0135: O2 Heater Circuit (Bank 1 Sensor 1)
• P0134: O2 Circuit No Activity Detected (Bank 1 Sensor 1)
• P0171: System Too Lean (Bank 1)
• P0172: System Too Rich (Bank 1)

Installation Tips: Perform replacement on a completely cool engine. Use a standard 22mm (7/8\") oxygen sensor socket and torque carefully according to factory vehicle service manual specifications.

Shipping, Warranty & Customer Support

• Fast Shipping: Orders are processed and dispatched within 1 business day.
• 30-Day Returns: Hassle-free 30-day return policy for unused items in original packaging.
• Warranty: Backed by a 1-Year Manufacturer Limited Warranty.
• Need Assistance? If you are unsure about vehicle compatibility, please contact us with your VIN (Vehicle Identification Number), year, make, model, and engine size before ordering. We are happy to help!