BDFHYK Oxygen Sensor Upstream Downstream O2, Compatible with GMC C2500 C3500 K2500 K3500, Compatible with Chevrolet Avalanche 2500 C2500 C3500, 234-4103, 12563345, Replacement 1PCS

This BDFHYK 234-4103 O2 sensor is an OE-style aftermarket replacement for listed Chevrolet Avalanche 2500, C2500, C3500 and GMC C2500, C3500, K2500 and K3500 applications. The exact upstream or downstream location varies by vehicle configuration. Before ordering, compare the original sensor number and confirm year, engine, emissions configuration, connector, wiring, lead length and exhaust position. A Check Engine Light or stored diagnostic code alone does not prove oxygen sensor failure.

234-4103 O2 Sensor Fitment for Chevrolet and GMC

• Chevrolet Avalanche 2500
• Chevrolet C2500
• Chevrolet C3500
• GMC C2500
• GMC C3500
• GMC K2500
• GMC K3500

The current product information does not provide complete year-and-engine mapping for these models. Confirm the exact application before installation.

234-4103 O2 Sensor Interchange References

Replacement references include 234-4103, 12563345, 12563346, 12565397, 12565414, 12616672 and 19209817. Match the reference together with the connector and original exhaust location.

234-4103 Upstream and Downstream Position Check

Position is application-dependent. Do not assign one universal upstream, downstream or Bank/Sensor location without service information for the exact vehicle and engine.

234-4103 O2 Sensor Diagnosis Before Replacement

Inspect the connector, wiring, heater circuit, related fuse, exhaust leaks, intake or vacuum leaks, fuel pressure, injector operation, misfires and catalyst condition before replacement. Fuel-trim and catalyst-efficiency codes require system diagnosis.

234-4103 O2 Sensor Installation Notes

• Allow the exhaust system to cool before service.
• Use an O2 sensor socket or suitable wrench.
• Compare the connector, lead length and original number with the removed sensor.
• Inspect bung threads and start the sensor by hand.
• Use anti-seize only when permitted by the sensor instructions.
• Tighten to the applicable service specification and route the harness safely.

234-4103 O2 Sensor Package Contents

• 1 × BDFHYK oxygen sensor

Important: This is an OE-style aftermarket replacement, not a factory-branded part.