Denso 234-9021 Air / Fuel Ratio Sensor - Upstream

Denso OE Style Air/Fuel Ratio Sensor

Denso 234-9021 is an OE Style heated air/fuel ratio sensor built for exact replacement and first-time fit. It is a specific-fit, 4-wire sensor with a male connector and a 14.17 in. wiring harness length for direct replacement on select Toyota and Lexus applications.

Key Features

• OE Style replacement air/fuel ratio sensor from Denso
• Heated sensor design for faster operating temperature
• Specific fit for direct application matching
• 4-wire configuration with male connector
• 14.17 in. wiring harness length
• Thread diameter: 0.711

Product Details

Denso 234-9021 is manufactured and tested to OE standards for accurate replacement on emission control systems. As an upstream air/fuel ratio sensor, it supports the engine management system by helping monitor exhaust mixture on select Toyota Avalon, Sienna, Solara, Camry, and Lexus ES300 models. This part cross-references Bosch 13540 for the same application.

The Denso OE Style line focuses on direct-fit replacement parts that match original equipment dimensions and connector design. That makes this sensor a practical choice when you need a replacement air/fuel ratio sensor for a 2000-2004 Toyota Avalon upstream, a 2001-2003 Toyota Sienna upstream, a 2001-2003 Toyota Solara upstream, a 2000-2001 Lexus ES300 upstream, or a 2001 Toyota Camry upstream. Denso 234-9021 is built for the right fit the first time.

What It Helps Address

• Check engine light related to air/fuel ratio sensor performance
• Rough idle caused by inaccurate mixture feedback
• Poor fuel control from a failing upstream sensor
• Emissions test failure tied to sensor response issues
• Delayed closed-loop operation after startup

Installation Notes and Tips

Confirm the upstream sensor location before ordering and match the connector style, wire count, and thread diameter to the original part. Inspect the harness routing and connector condition during replacement, and verify the application against the vehicle’s model year before installation. For fitment reference, this sensor fits 2000-2004 Toyota Avalon, upstream; 2001-2003 Toyota Sienna, upstream; 2001-2003 Toyota Solara, upstream; 2000-2001 Lexus ES300, upstream; and 2001 Toyota Camry, upstream.

Quality Assurance

Denso manufactures this sensor to strict OE standards and tests each component for replacement accuracy and consistent fit. The OE Style designation reflects a direct-replacement approach for vehicles that require factory-style sensor dimensions and connector compatibility.