O2 Oxygen Sensor Upstream Downstream for GMC Jimmy (1996-2001) 4.3L

Direct-Fit Upstream & Downstream O2 Sensor Kit for 1996-2001 GMC Jimmy (GMT330)

What it Does: This matched three-sensor kit restores closed-loop air-fuel metering and catalyst monitoring on the GMT330 1996-2001 GMC Jimmy L35 4.3L Vortec V6.

The Stock GMC Jimmy Sensor Failure

On the GMT330 chassis with the L35 4.3L Vortec V6, factory narrowband oxygen sensors suffer severe exhaust thermal cycling, carbon fouling, and moisture condensation inside the steel Y-pipe. Over time, repeated heat soak fractures the ceramic zirconia substrate while internal heater windings corrode and open-circuit. This sluggish voltage-switching response forces the PCM out of closed-loop fuel control, triggering P0135, P0141, P0155, and lean fuel-trim faults like P0171.

Common Symptoms of a Failing OEM Oxygen Sensor

• Check Engine Light / DTCs: P0135, P0141, or P0155 triggered by open heater circuits or slow switching.
• Rich/Lean Misfire Signs: Fuel-trim drift (P0171) causes rough idle, black exhaust soot, and hesitation.
• Failed Emissions & MPG Loss: Stuck PCM enrichment wastes fuel and fails OBD-II readiness tests.

The Direct-Fit Zirconia Oxygen Sensors Solution

Each sensor in this matched kit pairs a fast-light-off 4-wire heated zirconia ceramic element with a laser-welded stainless steel housing to resist moisture intrusion and exhaust gas contamination. Pre-coated anti-seize threads and OEM-length wiring harnesses with factory connectors allow true plug-and-play installation without splicing. Replacing both upstream Bank 1/Bank 2 sensors and the downstream catalytic monitor restores crisp closed-loop voltage switching between 0.1V and 0.9V.

What's Included

• 2 Upstream Oxygen Sensors
• 1 Downstream Oxygen Sensor

Technical Specifications

Compatibility

• 1996-2001 GMC Jimmy 4.3L

Frequently Asked Questions & Fitment Warnings

Does this fit the GMT330 Jimmy?

Yes. Direct fit for the 1996-2001 GMC Jimmy L35 4.3L Vortec V6. Confirm your 4.3L engine and 3-sensor exhaust layout before ordering.

Will this clear P0135, P0141, or P0155 codes?

Yes, when caused by worn sensors. New sensors restore proper heater resistance and voltage switching, clearing P0135, P0141, and P0155 once codes are reset.

Are connectors and install prep included?

Yes. Direct-fit harnesses plug straight into OEM connectors. Use a 22mm (7/8") O2 socket and avoid contaminating the sensor tip.

The GMC Heavy-Duty Standard

Engineered for thermal durability under towing and daily load on the GMT330 chassis, this kit keeps your L35 4.3L Vortec V6 running clean and CEL-free. Restore factory fuel trim accuracy with every mile.