FRONEZER Oxygen Sensor Set for Chevy Cruze/Sonic/Trax & Buick Encore 1.4L — 2PC Upstream + Downstream, OEM Fit

FRONEZER 2PCS oxygen sensor set (234-4528 upstream and 234-4529 downstream) replaces factory O2 sensors for specific 1.4L GM models to restore accurate air-fuel readings and stable engine performance.

If your Cruze, Sonic, Trax or Buick Encore with the 1.4L MFI engine is showing check-engine codes related to oxygen sensors or you're noticing rough idle, reduced fuel economy, or sluggish throttle response, swapping the upstream and downstream sensors can bring the exhaust monitoring system back to specification. These two sensors match the OEM part numbers and are built for heat resistance and corrosion protection to handle exhaust-system conditions without premature failure.

Which vehicles and engines will these sensors fit?

These FRONEZER O2 sensors are designed specifically for 1364cc (83 ci) 1.4L MFI engines used in select GM models. They are not compatible with the 1399cc DI (direct injection) 1.4L engines—verify your engine code before purchasing.

• Compatible: 2011–2015 Chevy Cruze 1.4L (Eco/LT/LTZ) and 2016 Cruze Limited 1.4L
• Compatible: 2012–2020 Chevy Sonic 1.4L and 2013–2020 Chevy Trax 1.4L
• Compatible: 2013–2021 Buick Encore 1.4L (MFI 1364cc only)
• Not compatible with 1.4L 1399cc DI engines—check vehicle details in main image

How do these replacement sensors match the original equipment?

FRONEZER supplies upstream and downstream sensors that correspond to common OEM reference numbers so they plug into the vehicle and communicate correctly with the engine control unit (ECU). They’re engineered to mirror original fit, thread size and connector type for a straightforward swap.

• Upstream replacement references: 234-4529, 55569903, 55572993
• Downstream replacement references: 234-4528, 55572216, 55574136
• Standard thread and connector styles to match factory harnesses
• Sold as a two-piece set (upstream + downstream) for complete exhaust monitoring restoration

What materials and construction features ensure longevity?

These sensors use high-grade stainless steel housings and ceramic sensing elements that tolerate high exhaust temperatures and resist corrosion from road salt and moisture. The design aims to deliver reliable oxygen-level feedback over many miles when installed and maintained correctly.

• Stainless-steel body for corrosion and heat resistance
• Ceramic sensing core for accurate oxygen detection
• Durable wiring and protective sheathing to withstand engine-bay conditions
• Quality controls to help reduce premature failure risks

What changes can I expect after replacing the faulty O2 sensors?

Once the upstream and downstream sensors are functioning, the ECU can fine-tune fuel delivery by using precise exhaust oxygen readings. Drivers typically notice smoother idling, crisper acceleration, and improved fuel economy when the air-fuel ratio is restored to proper levels.

• More consistent idle and fewer surges or stalls
• Improved throttle response and smoother acceleration
• Potential recovery of lost fuel efficiency
• Reduced emissions due to better combustion control

Who is this for: This FRONEZER 2-piece oxygen sensor kit is aimed at owners and independent mechanics who need a direct-fit, cost-effective replacement for failing O2 sensors on GM vehicles with the 1364cc 1.4L MFI engine. It’s a practical option for drivers seeing O2-related fault codes, decreased mileage, rough idle, or anyone restoring exhaust-sensing functionality without buying OEM-priced parts. Always confirm engine displacement and part compatibility before ordering to ensure a correct match.