O2 Oxygen Sensor Upstream Downstream for Mazda 3 6 CX-5 (2013-2018) 2.0L 2.5L

Direct-Fit Upstream & Downstream O2 Oxygen Sensor Kit for 2013-2018 Mazda 3,6,CX-5 (BM/BN, GJ/GL, KE)

What it Does: This matched upstream and downstream oxygen sensor kit monitors pre- and post-catalyst exhaust oxygen levels on 2013-2018 Mazda 3, 6, and CX-5 PE-VPS 2.0L and PY-VPS 2.5L engines to regulate air-fuel trims and verify catalyst efficiency.

The Stock Mazda 3,6,CX-5 Oxygen Sensor Failure

Factory oxygen sensors on the BM/BN, GJ/GL, and KE platforms endure severe thermal cycling near the high-compression SkyActiv exhaust manifold. Internal ceramic zirconia elements micro-fracture from heat soak, while oil ash or carbon fouling coats the sensing tip and slows voltage response. Additionally, internal heater circuits spike in resistance or burn open, triggering P0135, P0141, P0134, or P0171 codes and forcing rich open-loop fueling.

Common Symptoms of a Failing OEM Oxygen Sensor

• Check Engine Light & Heater DTCs: Codes such as P0134, P0135, P0141, or P2195 trigger due to open internal heater circuits or sluggish lambda switching.
• Erratic Fuel Trims & High Consumption: Corrupted upstream sensor feedback skews short- and long-term fuel trims, causing rich running and reduced MPG.
• Rough Idle & Emissions Failure: Delayed O2 response leads to idle hunting, throttle hesitation under load, and failed state OBD-II emissions inspections.

The Direct-Fit Matched O2 Sensor Solution

Replacing both sensors as a calibrated pair restores rapid closed-loop air-fuel control and accurate catalyst monitoring on PE-VPS and PY-VPS engines. Each unit features a stainless steel housing, laser-welded protective shroud, and fast-acting planar ceramic element engineered to resist thermal shock and exhaust moisture. Factory-length harnesses with OEM weatherproof connectors plug directly into the vehicle loom without splicing, replacing 234-4939, 234-8082, PEDD188G1, PE021886ZA, PE121886Z, and PEDE1886Z.

What's Included

• 1x Upstream Oxygen Sensor (Direct-Fit OEM Connector)
• 1x Downstream Oxygen Sensor (Direct-Fit OEM Connector)

Technical Specifications

Compatibility

• 2014-2018 Mazda 3 (BM/BN) — 2.0L and 2.5L
• 2014-2018 Mazda 6 (GJ/GL) — 2.5L
• 2013-2016 Mazda CX-5 (KE) — 2.0L
• 2014-2016 Mazda CX-5 (KE) — 2.5L

Frequently Asked Questions & Fitment Warnings

Does this fit the BM/BN, GJ/GL, and KE 3,6,CX-5?

Yes. This is a direct fit for the 2014-2018 Mazda 3 (BM/BN 2.0L/2.5L), 2014-2018 Mazda 6 (GJ/GL 2.5L), and 2013-2016 Mazda CX-5 (KE 2.0L 2013-2016; 2.5L 2014-2016) equipped with the PE-VPS or PY-VPS engine. Confirm engine displacement before ordering; excludes 2017+ CX-5 KF and 2.5T turbocharged models.

Will this clear P0135/P0141 codes and restore fuel trims?

Yes, when failed sensors or open heaters are the root cause. Installing this matched upstream and downstream set restores accurate lambda feedback to clear P0134, P0135, and P0141 after resetting DTCs; inspect harness wiring and check for exhaust leaks prior to installation.

Are the electrical connectors plug-and-play without splicing?

Yes. Both sensors feature factory-terminated OEM connectors for direct installation; apply O2-sensor-safe anti-seize only to the bung threads if not pre-coated, avoiding the sensing tip, and torque to factory specification.

The Mazda Precision Standard

Engineered for high-compression SkyActiv-G emissions precision, this matched sensor pair maintains exact stoichiometric air-fuel targets and ECU readiness. Expect consistent fuel economy, crisp throttle response, and CEL-free daily operation.