Denso 234-4391 Oxygen Sensor - Downstream

Denso 234-4391 Oxygen Sensor for Mazda 3

Denso 234-4391 is an OE-style heated oxygen sensor built for direct replacement in the downstream position on 2007-2013 Mazda 3 models. It is engineered for a specific fit and uses a 4-wire female connector with a threaded mount for straightforward application matching.

Key Features

• OE Style replacement oxygen sensor for precise application matching
• Heated sensor design for downstream exhaust monitoring
• Specific fit for 2007-2013 Mazda 3, downstream
• 4-wire configuration with female connector
• Threaded mounting type with 0.708 in. thread diameter
• 14.17 in. wiring harness length for vehicle-specific routing

Product Details

This Denso oxygen sensor is built to the strict standards associated with OE replacement parts, with attention to exact fit and consistent signal performance. The sensor uses Denso’s aluminum oxide trap layer to help protect the ceramic element from silicone and lead contamination, supporting stable engine management and long service life. If you are replacing a downstream oxygen sensor on a Mazda 3, Denso 234-4391 provides the correct OE-style configuration for the application.

This part cross-references Bosch 18073 for the same application.

What It Helps Address

• Check engine light concerns related to downstream oxygen sensor faults
• Incorrect exhaust oxygen readings affecting fuel control strategy
• Reduced fuel economy caused by a worn sensor
• Slow or inconsistent sensor response during closed-loop operation
• Fitment issues from using a universal sensor instead of a specific-fit part

Installation Notes

Verify the downstream location, connector style, wire count, and thread size before installation. Compare the original sensor routing and harness length to the replacement part to confirm proper placement on the Mazda 3 exhaust system. Use the vehicle’s service procedure for removal and installation to avoid damage to the exhaust bung or wiring.

Quality Assurance

Denso manufactures and tests this OE-style oxygen sensor to meet strict original-equipment standards for fit and performance. The design focus on exact replacement and contamination resistance supports dependable operation in the 2007-2013 Mazda 3 application.