Denso 234-4521 Oxygen Sensor - Downstream, Downstream Left or Downstream Right

Denso OE Style Oxygen Sensor 234-4521

Denso 234-4521 is an OE Style heated oxygen sensor built for direct replacement on select Lexus applications. It is engineered for a specific fit and uses a threaded mounting design with a male connector and 4-wire configuration for straightforward replacement on the correct downstream location.

Key Features

• OE Style replacement oxygen sensor for select Lexus vehicles
• Heated sensor design for faster operating response
• Specific fit for the listed downstream applications
• 4-wire construction with male connector
• Threaded mounting type with 0.708 in. thread diameter
• 21.65 in. wiring harness length
• Denso aluminum oxide trap layer helps protect the ceramic element from silicone and lead contamination

Product Details

Denso’s OE Style line is built and tested to OE standards for accurate replacement fit and dependable sensor performance. This oxygen sensor is designed for downstream use on Lexus IS F, GS350, IS250, IS350, GS450h, and GS430 applications listed in the fitment data. The Denso 234-4521 helps maintain proper exhaust feedback for engine management on vehicles that require a direct-fit downstream sensor. This part cross-references Toyota (e.g., 8946530730) for the same application.

What This Sensor Helps Address

• Check engine light caused by a failed downstream oxygen sensor
• Incorrect exhaust feedback readings from a worn sensor element
• Reduced fuel economy related to inaccurate air-fuel monitoring
• Slow sensor response after contamination or age-related wear
• Driveability issues tied to degraded emissions control performance

Installation Notes

• Verify the exact year, model, and downstream position before ordering.
• Match the connector style, wire count, and threaded mounting dimensions to the original sensor.
• Inspect the harness routing and connector condition during replacement.
• Use proper oxygen sensor service tools to avoid damaging the exhaust bung or wiring.
• Clear diagnostic trouble codes and confirm sensor operation after installation.

Quality Assurance

Denso manufactures this OE Style oxygen sensor to strict original-equipment standards and tests each component for replacement accuracy and first-time fit. The design includes an aluminum oxide trap layer to help protect the sensing element from silicone and lead contamination, supporting long-term sensor performance.