Kwiksen 234-4939 Downstream Oxygen o2 Sensor 2 Replacement For Mazda 3 L4 2.5L 2014-2016 / Mazda 6 L4 2.5L 2014-2015 Cylinder 2,3

In stock
Please check fitment notes & description for accurate information.


Brand New
Direct Plug-In Replacement.
4 wire configuration
Interchange Part Number: 234-4939, PE121886Z

Fit Vehicles:
Wiring Harness Length: 710mm/27.95 inch
Warranty: 1 Year
Built and tested to strict quality control standards

2014-2016 Mazda 3 L4 2.5L, Downstream; Cylinder 2,3
2014-2015 Mazda 6 L4 2.5L, Downstream; Cylinder 2,3

 Package Includes:

1x Downstream Oxygen Sensor

Must Know Before Buying:

The following information is for instructional and guidance reference only. We try and make them as accurate as we can.

If Check Engine Light is on or an OBDII Trouble/Fault code occurs after installation, check the sensor with a voltmeter as below. If the sensor is good, further diagnosis is required. There're many different codes for specific functional failures, which are NOT necessarily relevant to the sensor. Find out what the Code means before leaving any feedbacks.

Items that have been installed, altered or contaminated are non-returnable. ONLY a defective sensor after tested by a voltmeter is applied to the manufacturer warranty. 

20% restocking fee is required if the buyer bought wrong items due to not paying attention to fitment information and ask for a return.

The Price, Quality & Functionality of the O2 Sensor is fully covered under our warranty & return policy. However, a refund for any labor cost, expense in a dealer shop or damage due to the wrong installation is NOT covered.

Q: How do I know the O2 sensor is good or not? (Online Video)

A: The only way to know if the O2 sensor is functioning normally is to check its responsiveness to changes in the air/fuel mixture, by Voltage Measurement or Waveform Simulation.

Use a 10-megaohm digital voltmeter. Hook up the voltmeter's red probe to the sensor's signal wire and the black probe to engine ground. (Use back probe method, DO NOT pierce the wire.) For a good sensor, the voltage should fluctuate constantly between 0.1 and 0.9 volts after starting the engine for 2 or 3 minutes.

Please take a video clip of the voltmeter and contact us if our sensor:

  • Goes above range between 0.1 and 0.9 volt
  • Remains below 0.5 volts
  • Stays fixed at a particular voltage

You're free to choose replacement or refund if our sensor fails to work, in this case.

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