Aftertreatment NOx Lambda Sensor Cummins 4326862 1952565 3688978RX 5WK96751C

The 5WK96751C is a planar dual-cell limiting current type nitrogen oxide (NOx) sensor designed for 24V heavy-duty diesel engine exhaust aftertreatment systems. It is an electrochemical sensor that continuously measures 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 Selective Catalytic Reduction (SCR) system, ensuring compliance with Euro V, Euro VI, EPA, and equivalent emission standards.

The sensor is composed of a probe and a supporting electronic control system, mainly installed in the exhaust pipe of a diesel engine. It can directly measure the concentration of O₂ and NOx in the exhaust gas of the engine and send the signal to the engine electronic control unit (ECU) through the communication port.

Important: The 5WK96751C operates on 24V system voltage. It is not compatible with 12V passenger car electrical systems. This sensor is designed for commercial vehicle applications, including trucks, buses, and industrial equipment.

The following part numbers are directly interchangeable with 5WK96751C. 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, and voltage rating before purchasing.

• 4326862 – documented as OEM number for Cummins applications

• 4326470 – established cross-reference

• 1952565 – established cross-reference

• 2897309 – used in DAF applications

• 2872945 – established cross-reference

• 5WK96751, 5WK96751B, 5WK96751C – interchangeable variants

⚠️ Suffix and supersession caution: Different suffixes (C vs. A vs. B) may indicate minor production revisions or calibration differences. While these variants are generally interchangeable, different suffixes may have distinct CAN message IDs or heater calibration parameters. Match the full alphanumeric string on your original sensor whenever possible. Do not rely solely on partial number matches.

The 5WK96751C NOx sensor is designed for 24V commercial vehicle electrical systems and is widely used across medium-duty and heavy-duty diesel engine platforms. Application coverage spans Euro V / Euro VI / China 5/6 compliant commercial vehicles, including trucks, buses, and industrial machinery.

This sensor is most commonly associated with Cummins diesel engines in commercial vehicle applications. It is a critical component in the exhaust system of Cummins diesel engines, primarily used in commercial vehicles, industrial equipment, and various other applications. The sensor is applied to Cummins engine spare parts.

Based on cross-reference information and supplier listings, the 5WK96751C is compatible with the following engine platforms and vehicle types:

• DAF XF 106 – Euro 6 heavy-duty truck platform (sensor mounted in front of the catalytic converter)

• DAF XF – Heavy-duty truck platform

• Solaris Urbino – Transit bus application

The 5WK96751C is found in a wide range of 24V commercial vehicle applications:

• Heavy-duty trucks – long-haul and regional transport

• Medium-duty trucks – delivery and utility vehicles

• Transit buses and coaches – public transportation

• Construction equipment – with SCR aftertreatment systems

• Industrial equipment – diesel-powered machinery with emission controls

The sensor operates on a 24V power supply and includes ECU programming compatibility. This makes it suitable for most European and North American heavy-duty diesel platforms manufactured after the introduction of SCR-based emissions compliance systems.

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 including suffix (C, B, A, etc.)

2. Verify voltage – The 5WK96751C is a 24V sensor; confirm your vehicle electrical system is 24V

3. Count connector pins – Square four-needle gray connector type

4. Measure cable length – Approximately 600 mm

5. Check ECU compatibility – Some platforms require software adaptation after sensor replacement

6. Confirm thread size – M20 x 1.5 external thread (verify against original)

⚠️ Important note: Compatibility extends beyond physical fitment. The sensor must match the ECU’s CAN communication protocol. Different vehicle manufacturers may use different calibration parameters even when the physical sensor appears identical. Always reference your original sensor part number or consult vehicle-specific documentation before purchasing.

A degraded or failed 5WK96751C NOx sensor will typically trigger one or more of the following symptoms. Early recognition can prevent secondary damage to the SCR catalyst, DEF injector, or diesel particulate filter (DPF).

The most common first indicator. The ECU detects an out-of-range voltage, missing CAN message, or implausible NOx reading. On commercial vehicles, this appears as a CEL (Check Engine Light) or MIL on the dashboard.

Common codes associated with 5WK96751C NOx sensor failure include:

The P2200 code is specifically recognized when the NOx sensor transmits a load drop error (linear, binary lambda value, NOx signal or heater circuit) via the CAN bus. This condition occurs when at least one of the following error conditions has been recognized: NOx sensor wire open, linear lambda wire open, binary lambda wire open, or open wire in heater circuit.

• Intermittent: Wiring chafing, connector corrosion, or cracked solder joints. Symptoms appear on rough roads or during vibration. DTC may clear and return intermittently.

• Permanent: Heater open circuit, internal ceramic crack, or contamination from oil/soot/water. DTC returns immediately after clearing, and the sensor fails self-diagnostics.

Before replacing the 5WK96751C, perform these basic checks:

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

2. Heater resistance test – Measure between heater positive and heater ground pins using a multimeter. Typical resistance at 20°C is between 3-15 Ω. An open circuit or short indicates internal failure.

3. Voltage supply – With key on and engine off, verify 24V power at the sensor connector.

4. CAN bus integrity – Check CAN High and CAN Low lines for proper termination and absence of short circuits to ground or battery.

5. Live data review – Using a diagnostic scan tool, observe NOx readings with key on, engine off. It should read ambient air values (0-30 ppm). 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 degraded SCR catalyst. Perform a thorough system diagnosis before sensor replacement to avoid repeat failures.

Purchasing the correct 5WK96751C NOx sensor and installing it properly is essential for reliable SCR performance and avoiding costly mistakes. Commercial vehicle operators should pay special attention to electrical and communication compatibility.

• Match the full printed number on your original sensor, including the suffix (C, B, A, etc.). Different suffixes may have different CAN message IDs or heater calibration parameters.

• Check supersession information – If your original number has been superseded, confirm the new number is an approved replacement for your specific ECU calibration.

• Avoid “universal fit” listings – The 5WK96751C is a specific digital device; generic sensors claiming to fit “all 24V diesels” are unlikely to communicate correctly with your ECU.

• Reputable supplier – Choose a supplier with documented quality control (IATF 16949 or ISO 9001 certification) and a minimum 12-month warranty.

• 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 $65 to $120 for standard aftermarket options. Suspiciously low prices may indicate defective products. Genuine branded replacements (e.g., Schaeffler) may command higher prices, typically around $400+.

• Packaging – New sensors should be shipped in anti-static, moisture-proof packaging with a protective cap over the ceramic tip.

• 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.

• Use proper tools – Use clean, dry tools. If mechanical damage is found on the sensor, do not install it.

• Do not wipe anti-seize from threads – If present from the manufacturer, do not wipe lubricated threads clean.

Follow this sequence for proper installation:

1. Secure the ECU unit – Mount the sensor’s electronic control unit to the vehicle using screws. Follow the torque specifications from the vehicle’s installation table (maximum permissible torque less than 60 N/mm²).

2. Remove protective cap – Remove the protective cover from the sensor probe. Do not allow any dirt to contaminate the lubricated threads. Do not wipe anti-wear agent off the thread surface.

3. Install the probe – Insert the sensor probe into the exhaust pipe bung. Hand-tighten the hexagon nut while holding the sensor tip bottom section to prevent cable twisting and bending.

4. Torque properly – Use a standard torque wrench to tighten the hexagon nut. Recommended torque: 40–60 Nm (50 ± 10 Nm). After tightening, the maximum allowable cable rotation angle is 180°.

5. Connect the harness – Connect the mating connector to the sensor ECU connector. Ensure the connector interior is clean.

A new NOx sensor will not function correctly until the ECU learns its baseline values and performs a plausibility check. Follow these steps:

1. Install the sensor and securely connect the wiring harness.

2. Clear all existing DTCs using a professional scan tool capable of commercial vehicle diagnostics (e.g., J1939 compatible tool).

3. Perform “NOx sensor replacement adaptation” – 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.

4. Reset SCR learned values (if available) – This clears previously stored efficiency values from the old, potentially faulty sensor.

5. Drive cycle – Complete a 15-20 minute mixed driving cycle at operating temperature. For commercial vehicles, this may include both city and highway conditions with varying engine loads.

6. 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.

• Wiring harness condition: Commercial vehicles operate in harsh environments. 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 vehicle platforms use two NOx sensors (upstream and downstream of the SCR catalyst). 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.

• 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.

• Before purchasing, confirm the supplier offers a return or exchange for compatibility errors.

• 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 for your specific application if available.

• Most reputable suppliers offer a 12-month warranty against manufacturing defects.

The NOx Sensor 5WK96751C is a critical emissions aftertreatment component for 24V heavy-duty diesel commercial vehicles. It provides real-time NOx and O₂ measurement to the ECU for precise SCR control. Compatible with Cummins diesel engines, DAF trucks, and Solaris buses, this sensor is essential for Euro V / Euro VI compliance.

Proper selection (matching part number, voltage, connector type, and cable length), careful installation (using correct torque and handling procedures), 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 5WK96751C 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.