Yale 105-3 – Engine ECU: Intake Air Temperature (IAT) Sensor OORH (Out of Range High)

The signal voltage from the Intake Air Temperature sensor is exceeding the maximum acceptable threshold (typically >4.90 volts). This is usually caused by an open circuit in the sensor wiring harness, the sensor signal wire being shorted to a 5V reference voltage or battery voltage, an internal failure of the sensor itself, or a functional failure within the controller.

• Yale and Hyster Forklifts
• Yale and Hyster forklifts manufactured from 2005 and newer
• Mazda LPG
• GM
• PSI 2.0L / 2.4L
• Cummins QSB 3.3L

1. 1

   Inspect the IAT sensor wiring harness and connectors for physical damage, corrosion, or loose connections.

2. 2

   Use a multimeter to check for an open circuit in the sensor wiring.

3. 3

   Test the sensor signal wire to ensure it is not shorted to the 5V reference wire or to battery voltage.

4. 4

   Use a diagnostic handset or software to verify the controller commands and read the live sensor feedback to see if the voltage is pegged high.

1. 1

   Repair Wiring

   If the visual inspection or multimeter tests reveal damaged wires, shorts, or corroded connectors, repair or replace the affected wiring harness section. When splicing into a harness, use wire with high-temperature insulation and solder the splices for the best bond.

2. 2

   Replace the Sensor

   If the wiring and voltages check out but the sensor fails testing or the code remains active, replace the Intake Air Temperature (IAT) sensor.

3. 3

   Controller Replacement

   If the sensor and wiring are both confirmed good, the issue is likely a functional failure in the controller. Contact the Hyster-Yale Service department for authorization to replace the ECU.

4. 4

   Verification

   Clear/reset the error codes and monitor the sensor data live while the engine is running to verify the fix.