John Deere 105.04 – Engine Control Unit (ECU): The Intake Manifold Mixed Air Temp Sensor Low Voltage

The input voltage at the exhaust gas recirculation (EGR) mixed air temperature sensor (or intake manifold air temperature sensor) falls below the minimum specified level (typically below 0.1 V). This condition almost always indicates that the sensor has failed internally or that the sensor's signal wire is shorted to ground. When active, the engine may derate (limit power), alter combustion parameters, and disable active exhaust filter cleaning.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5065M
• 5075M
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5095M
• 5095MH
• 5105M
• 5015ML
• 5090M
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 5E Series
• 5M Series
• 6R Series
• 6430
• 7810
• 9030 Series
• 9230-9630
• 135D
• 444J
• 544J
• 624J
• 204L
• 304L
• 310K
• 310L
• 410K
• 7760
• CTS Combines

1. 1

   Inspect the wiring harness leading to the manifold air temperature sensor for rubbed-through insulation causing a short to ground, and check the connector pins for corrosion or damage

2. 2

   Use a multimeter or diagnostic tool to check the sensor voltage (a reading below 0.1 V confirms the fault)

3. 3

   Check the engine coolant level and inspect the radiator for debris (an air-locked low-temperature cooling circuit can cause low flow to the charge air cooler, triggering manifold temperature codes)

1. 1

   Prep the Machine

   Park the machine on a hard, flat surface, lower any attachments, and turn off the engine.

2. 2

   Clean the Cooling System

   Inspect and clean the radiator and cooling packages of any dust or debris, as restricted airflow can exacerbate intake temperature issues.

3. 3

   Bleed the LTC System (If Applicable)

   If your machine utilizes a Low Temperature Cooling circuit, ensure it is not air-locked. Fill the coolant reservoir to the 'MAX' line, open the bleed valve, and run the engine without a load for 5 minutes at 1700 RPM. Shut the engine off, check the level, and repeat until the coolant stays at the MAX line.

4. 4

   Locate the Sensor

   Locate the Intake Manifold Air Temperature Sensor (sometimes called the Boost Temperature Sensor) on the engine's air intake manifold.

5. 5

   Test the Circuit

   Disconnect the sensor. Turn the key to the ON position (engine off) and test the harness side for proper reference voltage (usually 5V). If the voltage is correct, the wiring is good, and the sensor itself has failed.

6. 6

   Replace the Sensor

   Unthread the faulty sensor from the manifold. Install the new sensor and tighten it to OEM specifications. Reconnect the electrical harness.

7. 7

   Clear Codes

   Use a diagnostic scanner to clear the ECU 000105.04 code and run the engine to verify the code does not return.