Car SCR Aftertreatment Outlet NOx Sensor Nitrogen Oxide 4326871 5WK96764B

The 5WK96764B is a planar dual-cell limiting current type nitrogen oxide (NOx) sensor designed for 12V commercial vehicle exhaust aftertreatment systems equipped with Selective Catalytic Reduction (SCR). It is an advanced electrochemical sensor that continuously monitors the concentration of nitrogen oxides (NOx) and oxygen (O₂) in the exhaust stream and communicates with the Engine Control Unit (ECU) via digital CAN bus protocol. This real-time feedback enables precise control of the SCR system and ensures compliance with Euro V, Euro VI, EPA 2010, China V/VI, and equivalent emission standards.

The sensor features a High-Temperature Co-fired Ceramic (HTCC) sensing element that provides excellent thermal stability and measurement accuracy across a wide range of operating conditions. The zirconium dioxide (ZrO₂) ceramic element serves as the core sensing material, enabling rapid detection of NOx and oxygen levels in the exhaust stream.

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

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

• Downstream (post-SCR) – installed after the SCR catalyst, primarily used to confirm that legislated emissions limits have not been exceeded

The sensor transmits NOx values in real time to the ECU after normal operation. The ECU monitors whether the NOx value in the exhaust gas exceeds the standard through a set of nitrogen oxide monitoring programs, adjusting DEF dosing accordingly to maintain emissions compliance.

Important: The 5WK96764B 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 5WK96764B. 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:

• 4326871 is listed as a high-quality replacement part designed for Cummins engines, monitoring and controlling NOx emissions to ensure regulatory compliance.

• 5WK96764A (4326871) is cross-referenced as a direct replacement for Cummins applications.

• A2C95994900-01 is referenced as the Continental OEM number for this sensor family.

• 5WK96764A (4326871/A045S168/A2C89789500-01) is listed for Cummins applications.

⚠️ Important: Different suffixes (5WK96764A vs. 5WK96764B) may indicate minor production revisions or calibration differences. Match the full alphanumeric string on your original sensor whenever possible. The underlying Continental reference number is the most reliable way to ensure correct functionality. If in doubt about compatibility, consult your original sensor's part number or contact the supplier before purchasing.

The 5WK96764B 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. Application coverage spans Euro V / EPA 2010 / China V compliant vehicles.

This sensor is most closely associated with Cummins diesel engines in commercial vehicle, truck, and bus applications. It plays a critical role in monitoring and controlling NOx emissions, ensuring vehicle compliance with emission regulations and efficient operation. The sensor is applied as original replacement equipment for Cummins engine applications.

Based on cross-reference information and supplier listings, the 5WK96764B and its cross-references are compatible with the following engine platforms:

Note: The sensor is compatible with both electronically controlled common-rail engines (ISB, ISC, ISL, ISX) as well as mechanical injection B series engines (4BTA3.9, 6BTA5.9) equipped with aftermarket or retrofitted SCR systems.

The 5WK96764B NOx sensor is widely used in commercial vehicles powered by Cummins diesel engines:

Source: Based on application data from OE cross-reference and supplier listings.

The 5WK96764B can be used in either upstream (pre-SCR) or downstream (post-SCR) positions depending on the specific vehicle platform. Always verify the correct position on your vehicle before installation, as some platforms use two NOx sensors while others may use only one.

• Upstream (pre-SCR) – installed before the SCR catalyst, providing real-time feedback to precisely meter DEF injection

• Downstream (post-SCR / Outlet) – installed after the SCR catalyst, used to confirm emissions compliance

The 5WK96764B is designed for vehicles meeting:

• Euro V – European emissions standards (primary specified standard)

• EPA 2010 – North American heavy-duty emissions standards

• China V / China VI – Asian market requirements

• Equivalent Tier standards for 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 5WK96764B or confirmed cross-references (4326871, A2C95994900-01, A045S168)

2. Verify voltage – The 5WK96764B 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 ISB, ISC, ISL, ISX, or F3.8 platforms

6. Verify mounting position – Upstream (pre-SCR) or downstream (post-SCR)

⚠️ 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. When repairing the SCR system, it is often recommended to replace both sensors to ensure they are working in sync.

A degraded or failed 5WK96764B 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.

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

Common codes associated with NOx sensor failure include:

The rationality check for this sensor consists of sensor stuck low and stuck high checks performed whenever the engine operates under highly transient conditions. A fault condition is reached whenever the NOx sensor values are below or above a fault limit. Faulty internal start-up behavior of the NOx sensor can cause the sensor to be evaluated as “not reliable," triggering these diagnostic codes.

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. This is a protective measure to prevent emissions compliance violations.

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. You may notice high fuel consumption, sudden jolts, or a jerky idle.

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 AdBlue depletion and potential crystallized injector.

A failing NOx sensor can result in erratic or unstable idling as the ECU compensates for inappropriate readings. You may notice high fuel consumption, sudden jolts, or a jerky idle.

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.

A malfunctioning NOx sensor can disrupt the SCR process, leading to improper DEF dosing. This may produce a strong ammonia or sulfur smell from the exhaust, indicating that the emissions control system is not functioning correctly.

Before replacing the 5WK96764B, 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 (OBD-II compatible), verify which codes are present and whether they are active or intermittent

3. Monitor live values – Observe sensor readings during engine operation

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

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

6. 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. When the SCR system is being repaired, it is often recommended to replace both sensors to ensure they are working in sync.

Purchasing the correct 5WK96764B 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 Continental number on your original sensor – 5WK96764B or confirmed cross-references (4326871, A2C95994900-01, A045S168)

• Check for suffix variations – Different suffixes (5WK96764A vs. 5WK96764B) may indicate minor production revisions or calibration differences

• Avoid “universal fit" listings – The 5WK96764B 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, contact the supplier with your original sensor’s part number before purchasing

• Reputable supplier – Choose a supplier with documented quality control (IATF 16949, ISO 14001, or TS16949 certification) and a minimum 6–12 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 $90 to $210:

  • Economy/standard aftermarket: $90–130

  • Premium aftermarket: $150–210

  • 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. Single product box containing one sensor

• After-sales service – Look for suppliers offering one-for-one compensation in case of manufacturing defects

• Core technology – Premium sensors feature advanced HTCC ceramic material technology and independent electronic control hardware designed by integrated circuits

• 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. Do not allow any dirt to contaminate the threads

• 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

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 and often triggers secondary Battery Management System faults.

Recommended procedure:

1. Install the sensor following the sequence above

2. Connect a professional diagnostic scan tool capable of commercial vehicle diagnostics (OBD-II 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. The ECU may command a specific warm-up sequence

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 (higher readings under heavy load, lower readings at idle)

Without proper adaptation, you may still see DTCs (e.g., P2200, P229E) even with a brand new sensor. Many returns are caused by skipped adaptation, not a defective part. If you are not comfortable with this procedure, professional installation is strongly recommended.

• 12V system confirmation: Unlike many other 5WK96xxx series NOx sensors that operate on 24V, the 5WK96764B 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 of the SCR catalyst). Verify which position requires replacement. When repairing the SCR system, it is often recommended to replace both sensors to ensure they are working in sync

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

• Emergency service: For breakdown or urgent fleet maintenance, some suppliers offer emergency-service channels for critical breakdown orders

• 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

• Commercial fleets subject to emissions auditing must maintain properly functioning SCR systems, including accurate NOx sensing

• The sensor meets EPA and EU emissions standards, ensuring legal operation and reduced environmental impact

• Before purchasing, confirm the supplier offers a return or exchange for compatibility errors, preferably within 30 days of receipt

• Keep your original sensor until the new one is confirmed working – it serves as the ultimate reference for part number and fitment

• Request a data sheet or installation guide that includes pinout and adaptation steps if available

• Most reputable suppliers offer a 6–12 month warranty against manufacturing defects. Some offer one-for-one compensation in case of manufacturing defects

The NOx Sensor 5WK96764B is a critical emissions aftertreatment component for 12V medium-duty and heavy-duty diesel commercial vehicles. Unlike many other sensors in the 5WK96xxx series which operate on 24V, the 5WK96764B is specifically designed for 12V systems and is primarily used with Cummins diesel engines in Foton, Dongfeng, Jianghuai, Freightliner, and Blue Bird commercial vehicle applications, meeting Euro V / EPA 2010 emission standards.

Key cross-references: 4326871, A2C95994900-01, A045S168, 5WK96764A

Key technical specifications:

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

• Measuring range: NOx 0–2500 ppm, O₂ 0%–21%

• Response time: λlin < 3500 ms, NOx < 3500 ms

• Warm-up time: < 100 seconds

• Design life: 6,000 hours or 350,000 km

• Thread: M20 x 1.5

• Torque specification: 40–60 Nm

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

• Compliance: Euro V, EPA 2010

Compatible engine platforms:

• Cummins ISB / ISBe / ISC / ISL / ISX

• Cummins F3.8 / QSB / QSL

• Cummins 4BTA3.9 / 6BTA5.9 (B series with SCR)

Vehicle applications (representative):

• Foton: Aumark (欧马可), Auman (欧曼)

• Dongfeng: Tianlong, Tianjin

• Jianghuai (JAC): Various light-to-medium trucks

• Blue Bird: All American FE, All American RE, Vision School Bus

• Freightliner: M2 106, M2 112, Cascadia

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 5WK96764B 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 even with a brand new sensor.

Advanced technology features: The sensor features High-Temperature Co-fired Ceramic (HTCC) technology with independent electronic control hardware designed by integrated circuits, embedded software, and calibration software. It has obtained multiple invention patents, utility model patents, and software copyrights, with system certification of ISO14001 and IATF16949.

Proper selection (matching the Continental part number 5WK96764B), 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 5WK96764B NOx sensor without compatibility issues or repeat failures.

For further technical support, refer to your engine or vehicle manufacturer's service documentation or consult a qualified diesel emissions specialist.