New Holland 3528 – ECM: NOx Sensor Signal Not Plausible

The Engine Control Module (ECM) has detected an implausible signal from one of the Nitrogen Oxide (NOx) sensors, indicating that the signal received is not within expected parameters. The data sent by the sensor is outside of the expected range or does not correlate correctly with other related engine parameters, such as engine load, exhaust temperatures, or the readings from the other NOx sensor. This plausibility issue affects the accurate monitoring of nitrogen oxide levels in the exhaust system and hinders the ECM's ability to accurately control DEF (AdBlue) injection. This fault will likely trigger a dash warning and may force the engine into a derated or 'limp mode' state to prevent excessive emissions.

• T6.120
• T6.140
• T6.150
• T6.155
• T6.160
• T6.165
• T6.175
• T7.170
• T7.270
• T8.275
• T8.435
• T9 Series
• CR Series

1. 1

   Visually inspect the entire wiring harness for the affected NOx sensor (both upstream and downstream) for chafing, melting, corrosion on connectors, or loose pins.

2. 2

   Inspect the exhaust system for any leaks upstream of the NOx sensor, as introduced oxygen can cause incorrect readings and plausibility faults.

3. 3

   Verify that the NOx sensor module is receiving the correct voltage and has a solid ground connection using a multimeter.

4. 4

   Remove the sensor probe from the exhaust bung and inspect for heavy soot buildup, moisture, or physical damage.

5. 5

   Check for any other active or stored fault codes related to the SCR system, DEF quality, or other engine sensors (e.g., temperature sensors or DEF injectors) that could cause a plausibility fault.

6. 6

   Monitor live data from both upstream and downstream NOx sensors using a diagnostic tool. On a fully warmed-up engine at idle, the upstream sensor should read between 150-400 ppm. A value frozen at zero or maximum indicates a failed sensor.

1. 1

   Allow exhaust to cool

   Ensure the exhaust system is completely cool before beginning work to prevent severe burns.

2. 2

   Disconnect the sensor

   Disconnect the electrical connector from the NOx sensor module and carefully release any wiring harness clips or heat shields.

3. 3

   Remove the sensor probe

   Using a correctly sized NOx sensor socket or wrench, carefully loosen and remove the sensor probe from the exhaust pipe. If seized, apply penetrating oil and gentle heat to the threaded bung, not the sensor itself.

4. 4

   Clean the bung

   Thoroughly clean the threads in the exhaust bung to remove any old anti-seize compound, rust, or soot.

5. 5

   Install the new sensor

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor, strictly avoiding the sensor tip.

6. 6

   Torque to specification

   Thread the new sensor in by hand to avoid cross-threading, then tighten it to the manufacturer's specified torque (typically between 40-60 Nm).

7. 7

   Reconnect and secure

   Reconnect the electrical connector and securely route the wiring harness away from heat sources and moving parts, using all original clips and brackets.

8. 8

   Clear fault codes and calibrate

   Use a diagnostic tool to clear the 3528 fault code and any related codes. Perform an SCR system recalibration or drive cycle as recommended to allow the ECM to adapt to the new sensor. This often involves a period of highway driving.