New Holland ENG 1801 – Engine Control Unit (ECU): Diesel Oxidation Catalyst (DOC) IN Temperature Sensor: Out of Voltage - High

The Engine Control Unit (ECU) is receiving a voltage signal from the DOC Inlet (IN) Temperature Sensor that exceeds the maximum expected threshold, which almost always points to an open circuit, a broken wire, an unplugged connector, or a short to a power source.

• L213
• L216
• L220
• L230
• C-Series
• B75D
• B90B
• B100B
• T6 Series
• T7 Series
• CX Harvesters
• Speedrowers

1. 1

   Locate the DOC IN Temperature Sensor mounted directly in the exhaust pipe at the inlet of the DOC/DPF assembly.

2. 2

   Inspect the sensor's pigtail wiring and the main engine harness connector for melted wires, pulled pins, or corrosion.

3. 3

   Disconnect the sensor and measure the resistance across its two pins with a multimeter. A reading of 'OL' (Open Loop) or infinite resistance indicates internal failure.

4. 4

   Turn the key to the ON position (engine off) and measure the voltage on the harness side of the connector. A 5V reference signal is expected; system voltage (12V/24V) indicates a short to power in the wiring harness.

1. 1

   Preparation

   Turn off the machine, remove the key, and disconnect the negative battery cable. Ensure the exhaust system has completely cooled down to prevent severe burns.

2. 2

   Disconnect

   Unplug the electrical connector for the DOC IN Temperature Sensor.

3. 3

   Removal

   Using a properly sized wrench or an exhaust sensor socket, carefully unscrew the sensor from the exhaust housing. Note: Due to extreme exhaust heat cycling, penetrating oil may be required to free the sensor threads without damaging the exhaust bung.

4. 4

   Installation

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor (if it does not come pre-coated). Thread the sensor in by hand to prevent cross-threading, then tighten to the OEM torque specification.

5. 5

   Reconnection

   Plug the sensor's electrical connector back into the engine harness. Secure any loose wiring with high-temp zip ties to keep it away from the hot exhaust pipe.

6. 6

   Clear Codes

   Reconnect the battery. Turn the ignition on and use a compatible diagnostic scan tool to clear the ENG 1801 fault code from the Engine ECU.

7. 7

   Validation

   Start the engine and monitor the DOC Inlet Temperature parameter on your diagnostic tool. Ensure the temperature rises smoothly as the exhaust heats up and that the fault code does not return.