Denso 234-4089 Oxygen Sensor - Downstream

OE-Style Heated Oxygen Sensor

Denso 234-4089 is an OE Style heated oxygen sensor built for specific-fit replacement on select Chevrolet Cavalier and Pontiac Sunfire applications. It is engineered for downstream use and uses a 4-wire, threaded design with a female connector for direct replacement service.

For drivers searching for a downstream oxygen sensor for 1999-2001 Chevrolet Cavalier or 1999-2001 Pontiac Sunfire, this Denso part number 234-4089 is built to match the original fit and electrical layout.

Key Features

• Heated oxygen sensor for downstream placement
• Specific-fit design for direct replacement
• 4-wire configuration with female connector
• Threaded mounting type with 0.708 in. thread diameter
• 49.21 in. wiring harness length
• OE Style construction for factory-style fit and function

OE Style Construction

Denso’s OE Style line is built to the same standards used for original equipment service, with precision manufacturing for accurate replacement fitment. The sensor uses an aluminum oxide trap layer to help protect the ceramic element from silicone and lead contamination, supporting stable engine management, fuel control, and long service life. Part number 234-4089 is a direct-fit oxygen sensor for vehicles that require a downstream heated sensor with the listed connector and thread specifications.

This part cross-references Bosch 13483 and NTK 21519 for the same application.

Vehicle Fitment

• Fits 1999-2001 Chevrolet Cavalier, downstream.
• Fits 1999-2001 Pontiac Sunfire, downstream.

Common Issues This Sensor Can Address

• Check engine light related to oxygen sensor performance
• Incorrect air-fuel mixture readings from a worn downstream sensor
• Reduced fuel economy caused by inaccurate exhaust feedback
• Slow sensor response from contamination or age
• Failed emissions testing tied to sensor malfunction

Installation Notes

Confirm downstream placement before installation and verify connector style, wire count, thread diameter, and harness length against the original sensor. Because this is a specific-fit threaded sensor, proper thread engagement and secure electrical connection are important for reliable operation. Always compare the old unit to the replacement part number 234-4089 before installation on a Chevrolet Cavalier or Pontiac Sunfire.

Quality Assurance

Denso manufactures and tests these oxygen sensors to OE standards for consistent fit and performance. The OE Style design is intended to provide a first-time fit with factory-style replacement accuracy.