CLAAS Id7779h / 7779h (2630 03) – ENG (A15): Input voltage of the fresh air intake temperature high

The engine control unit detects an abnormally high voltage signal from the fresh air intake temperature sensor (indicating a potential short to power or an open circuit). As a failsafe, the engine calculator defaults to an assumed intake fresh air temperature of 50°C, and the engine protection function related to the fresh air maximum temperature for the EGR (Exhaust Gas Recirculation) system is deactivated.

• Axion 810
• Axion 840
• Axion 850
• Axion 960
• Arion 410
• Arion 430
• Arion 510
• Arion 530
• Arion 550
• Arion 620
• Arion 640
• Arion 650
• Jaguar
• Lexion
• Tucano

1. 1

   Inspect the B222 fresh air intake temperature sensor for physical damage.

2. 2

   Check the wiring harness and connectors between the B222 sensor and the ENG (A15) module for short-circuits to 12V, open circuits, or severe corrosion.

3. 3

   Test the sensor's internal resistance using a multimeter to check for internal failure.

4. 4

   Check the power and ground sources (fuses, power supply, and ground connections) to the sensor circuit.

5. 5

   Verify the integrity of the ENG (A15) engine module if the sensor and wiring test perfectly.

1. 1

   Turn off the engine, remove the key, and disconnect the battery to prevent electrical shorts during repair.

2. 2

   Locate the B222 Fresh Air Intake Temperature Sensor on the engine's intake air circuit.

   Often located near or just after the charge air cooler/intercooler.

3. 3

   Disconnect the electrical pigtail from the B222 sensor. Inspect the pins on both the sensor and the harness for damage, moisture, or corrosion.

   Clean with contact cleaner if necessary.

4. 4

   Using a multimeter, test the wiring continuity from the sensor connector back to the ENG (A15) module pins.

   Repair any broken, chafed, or shorted wires.

5. 5

   Unthread/remove the B222 sensor from the intake piping.

   Do this if the wiring is intact but the sensor fails resistance testing (or if the fault persists after wiring repair).

6. 6

   Install the new fresh air intake temperature sensor and tighten it to the manufacturer's torque specifications.

   Reconnect the electrical harness.

7. 7

   Reconnect the battery, start the engine, and use the CLAAS Diagnostic System (CDS) or a compatible scan tool to clear the fault code.

   Verify that the sensor is now reading the correct ambient/intake temperature rather than the 50°C default.