WJIECO 4384393 NOx Sensor Durable. Cross references 4384393RX, SNS3012. 12V upstream engine outlet NOx Sensor for Cummins ISB4.5 / B4.5 CM2350 EPA17 GHG17 diesel engines. Fits Freightliner M2, Kenworth K270 T370, Peterbilt 535, International CV MV, Blue Bird and Thomas school buses, plug & play install.

4384393 NOx Sensor Overview

The 4384393 NOx Sensor manufactured by WJIECO is the upstream engine-out NOx sensor mounted before the SCR catalyst in the latest EPA17 / GHG17 SCR aftertreatment system for medium-duty vocational trucks and school buses powered by Cummins ISB4.5 and B4.5 diesel engines. This upstream NOx Sensor reads the NOx level coming straight out of the engine, so the ECM can calculate the correct DEF injection rate to keep emissions within compliance.

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This upstream signal is the foundation of closed-loop SCR control. If this NOx Sensor suffers signal drift, soot contamination, internal element failure or CAN communication loss, the ECM will log NOx-related DTCs, illuminate the check engine light, trigger engine power derate, and cause the vehicle to fail state emissions inspection. Many bus fleets and medium-duty repair shops encounter intermittent faults that only pop up under loaded operating conditions, which are classic symptoms of a degraded upstream NOx sensor. This sensor cross-references interchange numbers: 4384393, 4384393RX, SNS3012 for quick part matching for fleet managers, bus maintenance crews and independent diesel repair shops across the United States.

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WJIECO 2872946 NOx Sensor Durable Cross references 4326874, 2872946RX, 4326874RX, 5WK96741A, 5WK96741B. 24V downstream outlet NOx Sensor for Cummins ISB6.7, ISX11.9, ISX15 heavy-duty diesel engines. Fits Freightliner, Kenworth, Peterbilt, International, Western Star trucks, plug & play install.

H2: OEM-Grade Construction & Strict Factory Testing

Our 4384393 NOx Sensor uses a high-stability ceramic sensing chip, heavy-duty heat-resistant stainless steel probe housing and fully sealed wiring assembly with the OEM matching connector. It is built to withstand sustained high exhaust temperatures, continuous engine vibration, rapid thermal cycling, heavy soot loading, plus road salt, mud and moisture exposure year-round on transit and school buses and vocational medium-duty trucks. Low-cost generic NOx sensors often skip long-duration high-temperature burn-in calibration, which leads to signal drift and premature failure after only a short time in service.

Every finished 4384393 NOx Sensor passes a full set of factory quality validation steps: precision NOx signal calibration, high-temperature aging cycle test, waterproof seal pressure test and connector pin continuity inspection before packing. This rigorous QC process guarantees stable NOx readings, reliable CAN communication with the ECM and longer service life inside the demanding medium-duty diesel exhaust environment.

H2: Vehicle Fitment (Amazon US Medium Duty & Bus Fitment List)

Compatible Cummins Engines: Cummins ISB4.5, B4.5 CM2350 EPA17 / GHG17 Diesel (2017–2024)

• Freightliner: M2 106, M2 112
• International: CV Series, MV Series
• Kenworth: T270, T370, K270, K370
• Peterbilt: 325, 330, 337, 348, 535, 536
• Blue Bird: Vision, All American FE School Bus
• Thomas Built Bus: Saf-T-Liner C2

Important note: This is the 12V UPSTREAM ENGINE OUTLET NOx Sensor SNS3012. NOT compatible with ISB6.7, ISL9, ISX15 heavy-duty engines, NOT compatible with 12V Ram 2500/3500 pickup trucks. Verify your VIN, engine model, voltage rating, connector shape and original OEM part number before placing your order. Installing the wrong NOx Sensor will result in persistent SCR faults and derate that cannot be cleared easily.

Interchange OE Numbers: 4384393, 4384393RX, SNS3012

H2: Core Benefits of 4384393 NOx Sensor

Replacing your faulty upstream NOx Sensor with the WJIECO 4384393 NOx Sensor restores accurate engine-out NOx measurement for the SCR DEF dosing system. Reliable upstream NOx readings allow the ECM to maintain proper DEF injection rates, clear NOx and SCR related diagnostic trouble codes, remove engine power derate restrictions, and complete emissions readiness monitors required for DOT and state inspection. For school bus and medium-duty fleets, proactive replacement prevents unexpected downtime and disruptions to route schedules.

Robust, factory-calibrated construction greatly reduces early failure and intermittent fault codes that plague low-cost alternatives. This aftermarket NOx Sensor delivers OEM-matching performance at a much lower price than dealership replacement parts, making it a great fit for US school bus fleets, vocational truck operators and professional medium-duty diesel repair facilities.

H2: Plug-and-Play Installation, No Dealer Programming Required

This 4384393 NOx Sensor is a true direct-fit replacement for the factory upstream engine-out NOx Sensor on Cummins ISB4.5 / B4.5 CM2350 engines. Thread size, probe length, mounting thread, connector profile and wiring pinout all match OEM specifications exactly. Remove the old faulty sensor, torque the new sensor to factory torque specs and reconnect the stock wiring harness. There is no wire cutting, harness modification or ECU flash programming needed. After installation, clear all associated diagnostic trouble codes with a heavy-duty diesel scan tool and perform a loaded test drive. A full drive cycle is recommended so the ECM can run its SCR self-test and reset emissions readiness status.

Every WJIECO 4384393 NOx Sensor is fully bench tested before shipment. If you need a reliable 12V upstream NOx Sensor compatible with 4384393, 4384393RX and SNS3012 for Cummins ISB4.5 / B4.5 medium-duty trucks and school buses, this WJIECO NOx Sensor will return your SCR emissions system to normal operation.

Product Tags

4384393, 4384393RX, SNS3012, NOx Sensor, Nitrogen Oxide Sensor, Cummins ISB4.5 NOx sensor, Cummins B4.5 NOx sensor, upstream NOx sensor, Freightliner M2 NOx sensor, Kenworth K270 NOx sensor, Thomas C2 bus NOx sensor, medium duty truck NOx sensor, WJIECO exhaust sensor