Aftertreatment Upstream Inlet NOx Sensor Nitrogen Oxide 5WK96740 2500ppm

The 5WK96740 (also known as 5WK96740B or 5WK9 6740B) is a planar dual-cell limiting current type nitrogen oxide (NOx) sensor designed for 12V medium-duty and heavy-duty diesel engine exhaust aftertreatment systems equipped with Selective Catalytic Reduction (SCR). It is an electrochemical sensor that continuously measures the concentration of nitrogen oxides in the exhaust stream and communicates with the Engine Control Unit (ECU) via digital CAN bus protocol (SAE J1939). This real-time feedback enables precise control of the SCR system and ensures compliance with EPA 2010, Euro V, and equivalent emission standards.

The sensor is a CES Gen 2.8 design manufactured to Continental specifications, offering improved measurement accuracy and faster response compared to earlier generation sensors.

Most engines equipped with SCR aftertreatment systems utilize two NOx sensors:

• Upstream sensor (inlet) – installed before the SCR catalyst, providing real-time feedback to precisely meter Diesel Exhaust Fluid (DEF) injection

• Downstream sensor (outlet) – installed after the SCR catalyst, used mainly to confirm that legislated emissions limits have not been exceeded

The 5WK96740 sensor is typically used as an inlet (upstream) sensor in many applications, specifically designed to monitor the level of nitrogen oxide being emitted by diesel engines to ensure compliance with emissions regulations.

Important: The 5WK96740 operates on a 12V system voltage. Always verify your vehicle‘s electrical system voltage before purchase. Do not install on 24V systems as this will cause immediate and permanent damage to the sensor electronics.

The following part numbers are directly interchangeable with 5WK96740. When searching for a replacement, these numbers may appear on the original sensor label, in supplier catalogs, or in vehicle manufacturer documentation. Always verify physical connector type, cable length, voltage rating, and thread size before purchasing.

From multiple supplier sources, the following cross-references have been verified:

• The sensor is listed as a direct replacement for OEM numbers 2872944, 3687930, 4326870, A034M373, A045S167, and 5WK96740B

• DPFXFIT lists their SENN-0022XF sensor as an aftermarket replacement for select Cummins engines, built to OEM specifications with accurate NOx readings

• A standard cross-reference list for the 5WK96740B variant includes 4326870, 2872944, 3687930, 5WK96740B

• The sensor cross-references to 2872944, 5WK96740B, 4326874RX for inlet and outlet applications

• The sensor is also known as a CES Gen 2.8 sensor for Cummins engine platforms

⚠️ Important: The sensor is available in both 5WK96740 and 5WK96740B variants. While these are generally interchangeable, different suffixes may indicate minor production revisions or calibration differences. Match the full alphanumeric string on your original sensor whenever possible. Do not rely solely on partial number matches.

The 5WK96740 NOx sensor is designed for 12V commercial vehicle electrical systems and is primarily used with Cummins diesel engines in medium-duty and heavy-duty commercial vehicle applications. It is specifically designed for Cummins ISX, ISF, ISB, and other Cummins platforms meeting EPA 2010 emission standards.

This sensor is most closely associated with Cummins diesel engines in heavy-duty truck and commercial vehicle applications. It is a critical component for SCR aftertreatment systems on Cummins-powered trucks.

Based on cross-reference information and supplier listings, the 5WK96740 is compatible with the following engine platforms:

The 5WK96740 NOx sensor is widely used in commercial vehicles powered by Cummins diesel engines. Verified vehicle compatibility includes:

Source: Verified from multiple compatibility listings including partfinderq.com and eBay compatibility data.

The 5WK96740 is typically used as an inlet (upstream) sensor in many applications. For the Cummins ISX 11.9L and 15L engines (2013–2018), it is specifically designed as an inlet sensor for the exhaust aftertreatment system.

• Upstream (inlet) – Measures engine-out NOx before entering the SCR catalyst, providing real-time feedback to precisely meter DEF injection

• Downstream (outlet) – Some variants may be used in outlet position depending on the specific vehicle configuration

The specified mounting position of the sensor is typically downstream of the NOx trap or upstream of the SCR catalyst, depending on the engine configuration.

The 5WK96740 is designed for vehicles meeting:

• EPA 2010 (EPA10) – North American heavy-duty emissions standards (primary application)

• Euro V – European emissions standards

• China V / China VI – Asian market requirements

• Equivalent Tier standards for on-road and off-highway equipment

The sensor meets EPA and EU emissions standards, ensuring legal operation across regulated markets.

Due to the diversity of commercial vehicle configurations, physical fitment alone does not guarantee proper function. To confirm compatibility:

1. Check your original sensor label – Match the full part number 5WK96740 or 5WK96740B

2. Verify voltage – The 5WK96740 is a 12V sensor; confirm your vehicle electrical system is 12V

3. Count connector pins – 4-pin sealed connector type

4. Confirm thread size – M20 x 1.5

5. Check engine platform – Confirm compatibility with Cummins ISX, ISF, ISB, ISC, ISL, or ISX15 engines

6. Verify placement position – Confirm inlet (upstream) vs. outlet (downstream) position

7. Verify vehicle model year – Compatible with 2013–2015 model years (some applications up to 2018)

⚠️ Important note: Compatibility extends beyond physical fitment. The sensor must match the ECU‘s CAN communication protocol. Always reference your original sensor‘s part number or consult vehicle-specific documentation before purchasing.

A degraded or failed 5WK96740 NOx sensor will typically trigger one or more of the following symptoms. Early recognition can prevent secondary damage to the SCR catalyst, DEF injector, Diesel Exhaust Fluid system, or Diesel Particulate Filter (DPF).

The most common first indicator is the illumination of the check engine light on your dashboard. The ECU detects abnormal, missing, or out-of-range NOx data and triggers a fault code. A faulty NOx sensor often illuminates the vehicle‘s check engine light.

The rationality check for this sensor consists of sensor stuck low and stuck high checks performed whenever the engine operates under highly transient conditions.

When NOx readings become inconsistent or implausible, the ECU reacts to protect emissions systems by limiting torque and engine speed. Commercial vehicles may experience speed limitation or restricted RPM until the issue is resolved.

A malfunctioning NOx sensor sends inaccurate data to the ECU, which in turn adjusts the air-fuel mixture incorrectly. This imbalance often causes the engine to inject more fuel than necessary, leading to increased fuel consumption and higher operating costs.

A faulty NOx sensor disrupts the ECU and SCR, triggering fault codes and leading to incorrect DEF dosing. False high NOx readings cause the SCR to over-dose DEF, resulting in rapid DEF depletion and potential crystallized injector. This is one of the most costly indirect symptoms of a failing NOx sensor.

Since the NOx sensor directly impacts your vehicle‘s emissions, a failure can cause your vehicle to exceed acceptable limits, resulting in a failed test.

When the NOx sensor is unable to maintain a reliable output, its signal quality will be set to “not reliable.” Too long a duration of unreliable sensor signal quality is considered an error. This OBD monitor is designed to detect bad sensor quality.

Before replacing the 5WK96740, perform these basic checks:

1. Visual inspection – Look for damaged cable insulation, chafing against chassis components, bent pins, or a melted/cracked connector

2. Check DTC status – Using a diagnostic scan tool, verify which codes are present and whether they are active or intermittent

3. Heater resistance test – Measure between heater positive and heater ground pins using a multimeter. An open circuit or short indicates internal failure

4. Voltage supply – With key on and engine off, verify 12V power at the sensor connector

5. Live data review – Observe NOx readings; a fixed reading of 0 ppm or pegged at maximum without change points strongly suggests a faulty sensor

Note: A recurring NOx sensor code may also be caused by an exhaust leak upstream of the sensor, poor DEF quality, a failed DEF injector, or a contaminated SCR catalyst. Perform a thorough system diagnosis before sensor replacement to avoid repeat failures.

Purchasing the correct 5WK96740 NOx sensor and installing it properly is essential for reliable SCR performance and avoiding costly mistakes. Commercial vehicle operators should pay special attention to voltage compatibility, correct identification of the Continental reference number, and installation procedures.

• Match the full printed number on your original sensor – 5WK96740 or 5WK96740B

• Check OEM cross-references – Verify compatibility with numbers such as 2872944, 3687930, 4326870, A034M373, A045S167

• Check for suffix variations – Different suffixes (5WK96740 vs. 5WK96740B) may indicate minor production revisions or calibration differences. Do not rely solely on partial number matches

• Avoid “universal fit” listings – This is a specific digital device; generic sensors claiming to fit “all diesels” are unlikely to communicate correctly with your ECU

• If in doubt about compatibility, refer to your original sensor‘s part number or consult a specialist before purchasing

• Reputable supplier – Choose a supplier with documented quality control and a minimum 12-month warranty. Many premium suppliers offer 12-month, unlimited mileage coverage

• Avoid used or “remanufactured” – NOx sensors degrade internally from heat and contamination. Used sensors almost always fail prematurely

• Price guideline – Authentic quality replacements typically range from approximately $150 to $350. Suspiciously low prices may indicate counterfeit or defective products

• Packaging – New sensors should be shipped in protective packaging with a protective cap over the ceramic tip

• After-sales service – Some suppliers offer one-for-one compensation in case of manufacturing defects

• Do not touch the ceramic sensing tip – Skin oils cause thermal shock cracking during the first heat-up cycle

• Inspect cable routing – Ensure the new cable follows the original path, using existing clips and standoffs. Avoid sharp bends or contact with moving parts

• Remove protective cap only when ready – Keep the sensor clean by removing the protective cap immediately before installation

• Clean the bung threads – Use a thread chaser (M20 x 1.5) to remove carbon buildup and rust before installation

• Inspect electrical connections – Check the vehicle-side connector for cleanliness, corrosion, and sealing integrity before installing the new sensor

Follow this sequence for proper installation:

1. Prepare the mounting location – Allow the exhaust system to cool before removal. Wear heat-resistant gloves and eye protection

2. Remove the old sensor – Carefully remove the faulty sensor from the exhaust bung

3. Inspect the vehicle connector – Ensure the mating connector is dry, clean, and free from corrosion

4. Remove protective cap – Immediately before installation, remove the protective cover from the sensor probe

5. Install the probe – Insert the sensor probe into the exhaust bung. Hand-tighten while holding the sensor body to prevent cable twisting

6. Torque properly – Recommended torque for M20 x 1.5 threads: 40–60 Nm (use a torque wrench)

7. Connect the harness – Connect the mating 4-pin connector to the sensor. Ensure the connector interior is clean and dry

8. Secure the cable – Use original routing clips and standoffs to secure the harness away from heat sources and moving parts

A new NOx sensor will NOT function correctly until the ECU learns its baseline values and performs a plausibility check. Many returns are caused by skipped adaptation, not a defective part.

Why adaptation is necessary: Engine Control Units continuously learn and adapt to sensor degradation over time. Installing a fresh component without resetting these learned values leaves your ECU operating on outdated, skewed data.

What DOES NOT work: Attempting to clear deep-level adaptation memory by disconnecting the battery is ineffective on modern emissions systems.

Recommended procedure:

1. Install the sensor following the sequence above

2. Connect a professional diagnostic scan tool capable of commercial vehicle diagnostics (SAE J1939 compatible)

3. Clear all existing DTCs – Use the diagnostic tool to clear all existing fault codes

4. Perform “NOx sensor reset / adaptation / teach-in” – This function is typically found under “Special functions,” “SCR system,” or “Aftertreatment service” in diagnostic software

5. Reset SCR learned values (if available) – This clears previously stored efficiency values from the old sensor

6. Drive cycle – Complete a 15–20 minute mixed driving cycle at operating temperature with varying engine loads

7. Verify readiness – After the drive cycle, check for any returning DTCs. Monitor live NOx data; it should fluctuate logically

⚠️ Without proper adaptation, you may still see DTCs (e.g., P2200, P229E) even with a brand new sensor.

• 12V system confirmation: Unlike many other 5WK96xxx series NOx sensors that operate on 24V, the 5WK96740 is a 12V sensor. Verify your vehicle‘s electrical system voltage before purchase

• Wiring harness condition: Commercial vehicles operate in harsh environments (vibration, heat, moisture, road salt). Inspect the full harness length for chafing, corrosion at connectors, and damaged insulation before condemning the sensor

• SCR system health: A recurring NOx sensor code may indicate a failed SCR catalyst, DEF quality issues, or a clogged DEF injector. These should be diagnosed before replacing the sensor a second time

• Multiple sensor positions: Some platforms use two NOx sensors (upstream and downstream). Verify which position requires replacement

• ECU software updates: In some cases, a recurring NOx sensor issue may be addressed by an ECU software update rather than repeated sensor replacement

• CES Gen 2.8 technology: This sensor features advanced HTCC ceramic sensing technology for improved measurement accuracy

• In regions with mandatory emissions testing (EU, California, China, Australia, Brazil), a non-functioning NOx sensor will cause the MIL to illuminate, resulting in automatic inspection failure

• It is illegal to defeat, delete, or simulate the NOx sensor signal in any on-road vehicle. Always replace with a fully functional sensor

• The sensor is designed to detect NOx levels in diesel-fueled vehicles to comply with state and federal emissions regulations

• The sensor is designed to optimize emissions and fuel economy to meet national and regional emission standards

The NOx Sensor 5WK96740 is a critical emissions aftertreatment component for 12V medium-duty and heavy-duty diesel commercial vehicles powered by Cummins engines. Unlike many other sensors in the 5WK96xxx series which operate on 24V, the 5WK96740 is specifically designed for 12V systems and is primarily used in Freightliner, Kenworth, Peterbilt, Western Star, and Volvo trucks meeting EPA 2010 emission standards.

Key cross-references: 5WK96740B, 2872944, 3687930, 4326870, A034M373, A045S167, 5EL012, NOX-CXX-007, SENN-0022XF

Key technical specifications:

• Operating voltage: 12V DC (critical distinction – NOT 24V)

• Connector: 4-pin sealed

• Thread: M20 x 1.5

• Torque specification: 40–60 Nm

• Certifications: TS16949, CE, CCC, ISO14001, IATF16949

• Compliance: EPA10, Euro V, China V/VI

Compatible engine platforms:

• Cummins ISX15 (11.9L – 15L) – 2007–2018 model years

• Cummins ISF (2.8 / 3.8 / 4.5)

• Cummins ISB / ISD / ISBE (3.9L – 6.7L)

• Cummins B Series (B3.9, B4.5, B5.9, B6.7)

• Cummins ISC / ISL / QSB (industrial)

• Cummins ISG (ISG11 / ISG12)

Vehicle applications (representative):

• Freightliner: Cascadia, Coronado, Columbia, ProStar (2013–2015)

• Kenworth: C500, T660, T680, T700, T800, T880, W900 (2013–2015)

• Peterbilt: 320, 365, 367, 384, 386, 388, 389, 567 (2013–2015)

• Western Star: 4900FA, 4900SA, 4900EX, 6900XD (2013–2015)

• Volvo: VNL (2013–2015)

Installation requirements:

• Do NOT apply anti-seize to threads

• Do NOT touch ceramic sensing element

• Confirm 12V system voltage – DO NOT install on 24V vehicles

• Professional installation and mandatory ECU adaptation required after replacement

• Perform torque to 40–60 Nm

CRITICAL NOTE – VOLTAGE COMPATIBILITY: The 5WK96740 operates on 12V DC. This distinguishes it from many other NOx sensors in the 5WK96xxx series that are designed for 24V commercial vehicle applications. Always verify your vehicle‘s electrical system voltage (12V or 24V) before purchase. Installing this 12V sensor on a 24V system will cause immediate heater or electronics damage.

CRITICAL NOTE – ECU ADAPTATION IS MANDATORY: A physical NOx sensor replacement must be paired with an ECU adaptation or reset to clear permanent fault codes and restore SCR efficiency. Disconnecting the battery will NOT work. Without proper adaptation, you will still see DTCs (P2200, P229E) even with a brand new sensor.

CRITICAL NOTE – FAILURE PREVENTION: A faulty NOx sensor can cause DPF failures and excess fuel usage. Address NOx issues promptly to avoid costly DPF replacements and fuel waste.

CES Gen 2.8 technology: The sensor features advanced HTCC ceramic sensing element technology for improved measurement accuracy and durability.

Proper selection (matching the part number 5WK96740 and confirmed cross-references), confirmation of 12V system voltage, careful installation using correct torque (40–60 Nm), and mandatory ECU adaptation ensure full emissions compliance, optimal fuel economy, and reliable SCR system performance. Use this guide to confidently purchase and replace a failed 5WK96740 NOx sensor without compatibility issues or repeat failures.