4-Pin 1.65mm Waterproof O2 Sensor Connector – Buick Cadillac GMC Chevrolet

A 4-pin 1.65mm pitch IP68 waterproof male and female connector set for oxygen (O2/lambda) sensor harness repair on GM platforms including Buick, Cadillac, GMC, and Chevrolet. The 1.65mm pitch is the standard GM O2 sensor connector format used across multiple engine families and model years.

Key Specifications

• Pin Count: 4
• Gender: Male & Female set (with wire)
• Terminal Pitch: 1.65mm (GM standard O2 sensor format)
• Wire Gauge: 20 AWG (0.5 mm²)
• Wire Length: 5.5 inches (140 mm)
• Waterproof Rating: IP68
• Housing Material: PA66 glass-filled nylon
• Terminal Material: Copper alloy, tin-plated
• Current Rating: Up to 5A per pin

GM O2 Sensor Pin Assignment (4-Pin Heated)

Compatible GM Applications

• Buick LaCrosse / Enclave / Regal: Pre-cat and post-cat O2 sensor harness connector
• Cadillac CTS / SRX / Escalade: Lambda sensor harness connector
• GMC Sierra / Yukon / Terrain: O2 sensor harness connector
• Chevrolet Malibu / Equinox / Silverado / Cruze: O2 sensor harness connector

GM O2 Sensor Heater Circuit – How It Works

GM uses an ECM-controlled low-side heater ground (Pin B) rather than a simple chassis ground. The ECM switches Pin B to ground to activate the heater, allowing it to monitor heater current and detect open/short circuit faults. This means Pin B will not show continuity to chassis ground with the connector unplugged – this is normal and does not indicate a wiring fault.

Diagnosis – GM O2 Sensor Faults

• P0135 / P0141 / P0155 / P0161 (Heater Circuit): Check Pin A (12V supply) and Pin B (ECM ground) – an open circuit at the connector prevents heater activation
• P0130–P0167 (O2 Sensor Signal Circuit): Inspect connector before replacing sensor – a corroded terminal is a common root cause on GM platforms
• Rich running / high fuel trim: A corroded O2 signal connector causes the ECM to read a lean signal and add fuel – check connector before replacing sensor

FAQ

Q: Why does Pin B on my GM O2 sensor connector not show ground with a multimeter?
A: Pin B is an ECM-controlled low-side ground – it only shows ground when the ECM activates the heater circuit with the engine running. This is normal GM design and does not indicate a wiring fault.

Q: Can I use this connector for both upstream and downstream O2 sensors on GM?
A: Yes – GM uses the same 4-pin 1.65mm connector format for both pre-cat (upstream) and post-cat (downstream) heated O2 sensors across most platforms.

Package Contents

1 × 4-Pin Male Connector + 1 × 4-Pin Female Connector, each with 20 AWG wire and terminal insert