Denso 234-4144 Oxygen Sensor - Downstream or Upstream

Denso OE Style Oxygen Sensor 234-4144

Denso 234-4144 is an OE Style heated oxygen sensor built for direct replacement and precise fitment. It is engineered for Mazda Miata, Mazda 323, and Mazda Protege applications where accurate exhaust feedback is needed for proper engine management.

The OE Style line focuses on first-time fit and factory-style replacement dimensions. This sensor uses a threaded mounting design, a female connector, 4 wires, and a 29.13-inch wiring harness length for a direct-install layout on the listed vehicles.

Key Features

• Heated oxygen sensor for faster operating response
• Specific fit design for listed Mazda applications
• Threaded mounting type for direct replacement
• Female connector with 4-wire configuration
• 29.13-inch wiring harness length
• 0.708-inch thread diameter
• OE Style replacement built to match factory fitment

OE Style Replacement Details

Denso’s OE Style product line is built around exact replacement dimensions and factory-style fitment. For this application, that means a sensor designed to match the original mounting and connector layout on compatible Mazda Miata, Mazda 323, and Mazda Protege models. The part number 234-4144 is also listed among common cross-reference numbers for the same application, including Bosch 15330 and NTK 22502.

What This Sensor Helps Address

• Check engine light caused by oxygen sensor failure
• Rough idle or inconsistent air-fuel feedback
• Reduced fuel economy from inaccurate exhaust readings
• Slow sensor response during closed-loop operation
• Emissions test failures tied to a worn sensor

Fitment and Installation Notes

• Fits 1999-2000 Mazda Miata, upstream, excluding California; OE Style
• Fits 1999-2000 Mazda Miata, downstream, California exempt parts can be used on pollution controlled vehicles in California; OE Style
• Fits 1994-1997 Mazda Miata, upstream; OE Style
• Fits 1995 Mazda 323, upstream, DOHC; OE Style
• Fits 1993-1994 Mazda 323, upstream, 4 Lead Sensor; OE Style
• Fits 1993-1994 Mazda Protege, upstream, 4 Lead Sensor; OE Style

Verify the sensor position, connector style, and thread size before installation. On Mazda Miata, Mazda 323, and Mazda Protege applications, matching the upstream or downstream location is essential for correct operation. Use the existing harness routing and connector orientation as a reference during replacement.

Quality Assurance

Denso manufactures and tests this oxygen sensor to OE standards for consistent replacement performance. The sensor uses an aluminum oxide trap layer to help protect the ceramic element from silicone and lead contamination, supporting long service life and stable engine control.