BELKEBIR Oxygen Sensor 2-Pack Upstream & Downstream for 1.4L Chevy/Buick (2011–2021) — Factory Fit, Durable

BELKEBIR 2-pack upstream and downstream oxygen sensors (234-4528 & 234-4529) replace worn O2 units on 1.4L Chevy Cruze, Sonic, Trax and Buick Encore models to restore accurate air-fuel monitoring and emission control.

If your check engine light, poor fuel economy or rough idle points to an oxygen sensor issue, this matched pair from BELKEBIR is made to meet the factory fitment and wiring for the specified 1.4L L4 engines. Each sensor is constructed with durable materials and calibrated to supply reliable voltage signals to the engine computer, helping return drivability and emissions performance to expected levels. The set includes both upstream (pre-catalyst) and downstream (post-catalyst) sensors so you can address common failure points in one service.

Which vehicles and engines are these oxygen sensors compatible with?

These sensors are designed for 1364cc (83 ci) 1.4L MFI engines used in specified GM models. They fit many model years listed but do not work with the 1399cc DI 1.4L variant.

• 2011–2016 Chevy Cruze (1.4L L4, select models)
• 2012–2020 Chevy Sonic (1.4L L4)
• 2013–2020 Chevy Trax (1.4L L4) — check engine code before ordering
• 2013–2021 Buick Encore (1.4L L4)

How do these replacement part numbers line up with OEM references?

The BELKEBIR set corresponds to commonly referenced OE numbers so you can match parts with confidence. Upstream and downstream items are identified separately for proper placement and diagnostics.

• Upstream (pre-catalyst): 234-4529, 2344529, 55569903, 55572993
• Downstream (post-catalyst): 234-4528, 2344528, 55572216, 55574136
• Sold as a two-piece kit to cover both positions at once

What performance and durability features should I expect from these sensors?

BELKEBIR sensors are built with long-lasting internal materials and finished to withstand the underhood environment. They deliver timely oxygen readings so the engine control module can adjust fuel trim properly.

• Platinum and ceramic sensing elements for stable, repeatable signals
• Heat-resistant housings and seals to endure exhaust temperatures
• Factory-style connectors and wiring lengths for straightforward installation
• Designed to reduce false fault codes and smooth engine operation

How will replacing both upstream and downstream sensors affect driving?

Installing matched sensors helps the vehicle maintain correct air-fuel balance and emissions monitoring. Drivers often notice more consistent idling, quicker throttle response and improved fuel use after replacing failing sensors.

• Stabilizes fuel trim adjustments for better MPG potential
• Improves catalytic converter monitoring and emissions readings
• Helps clear oxygen-sensor-related trouble codes when problems are fixed

Who is this for: This two-piece BELKEBIR O2 sensor kit is aimed at DIYers, independent shops and fleet mechanics who need a dependable, vehicle-specific upstream and downstream replacement for GM 1.4L MFI engines. Confirm your engine displacement and OE part numbers before purchase to ensure compatibility with your Chevy Cruze, Sonic, Trax or Buick Encore. If your vehicle shows oxygen sensor diagnostic codes, decreased fuel economy, or uneven idle, this matched sensor set gives a direct-replacement option to restore accurate exhaust oxygen measurement and support proper engine control system function.