New Holland ENG 3954 – Engine ECU: Exhaust Gas Temperature 2 Sensor Signal Too Low

The voltage signal returning from the Exhaust Gas Temperature (EGT) Sensor 2 to the control module has dropped below the minimum expected threshold. This condition is almost always caused by an open circuit, a short to ground in the sensor's wiring harness, or a completely failed sensor element (which is a PTC - Positive Temperature Coefficient thermistor).

• L216
• L218
• L220
• L223
• L225
• L228
• L230
• C227
• C232
• C238
• W50C
• W60C
• W70C
• W80C
• W130C
• W170C
• W190C
• W230C
• W270C
• W300C
• B90B
• B100B

1. 1

   Visual Inspection: Locate Exhaust Gas Temperature Sensor 2 (typically located downstream of the turbocharger, near the Diesel Oxidation Catalyst (DOC) or Diesel Particulate Filter (DPF)). Inspect the wiring harness for chafed wires, melted insulation from exhaust heat, or physical damage.

2. 2

   Connector Check: Disconnect the 2-pin sensor connector. Inspect the pins for corrosion, moisture, or pushed-out terminals.

3. 3

   Circuit Testing: Turn the key to the ON position (engine off). Use a digital multimeter to verify that the Engine ECU is supplying the correct reference voltage (usually 5V) to the harness side of the connector. Check the signal wire for a short to ground.

4. 4

   Sensor Testing: Measure the resistance across the sensor's two terminals. An infinite resistance reading (open circuit) or zero resistance (dead short) confirms the sensor itself has failed internally and must be replaced.

1. 1

   Safety First

   Power down the machine, remove the key, and disconnect the negative battery cable. Crucial: Allow the exhaust system to cool completely to prevent severe burns.

2. 2

   Locate the Sensor

   Find EGT Sensor 2 on the exhaust aftertreatment piping.

3. 3

   Disconnect

   Unplug the electrical connector from the sensor harness.

4. 4

   Prep for Removal

   Because exhaust sensors undergo extreme heat cycles, they frequently seize. Spray a high-quality penetrating oil on the sensor threads and allow it to soak for several minutes.

5. 5

   Remove the Sensor

   Using an appropriately sized wrench or a specialized slotted sensor socket, carefully unscrew the EGT sensor from the exhaust pipe.

6. 6

   Install the New Sensor

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor (if it doesn't already have pre-applied thread paste). Do not get any anti-seize on the sensor probe itself. Thread the sensor in by hand to prevent cross-threading, then tighten to the OEM torque specification.

7. 7

   Reconnect

   Plug the 2-pin electrical connector back in, ensuring the locking tab clicks securely into place.

8. 8

   Clear Codes

   Reconnect the battery, start the engine, and use a diagnostic scan tool to clear the ENG 3954 fault code. Monitor the live data to ensure the EGT 2 sensor is now reading a plausible temperature.