AHT Cooling Systems E02

What does AHT Cooling Systems E02 mean?

The control board detects a fault in the suction gas temperature sensor (suction manifold sensor). This NTC or thermistor probe monitors refrigerant temperature at the suction line to calculate superheat. A broken wire, failed sensor, or out-of-range reading causes E02, preventing accurate superheat control and potentially triggering compressor protection.

Symptoms

• E02 fault code on display with red LED.
• Buzzer activates to alert staff.
• Superheat control disabled; EEV reverts to a safe default position.
• Cabinet temperature may drift above or below setpoint.

Common causes

• Suction gas temperature sensor (suction manifold sensor) open-circuit or short-circuit failure.
• Wiring harness between sensor and control board damaged or connector loose.
• Sensor displaced from its mounting point on the suction line.
• Corrosion or moisture ingress at sensor connector.
• Control board sensor input channel failure.

Diagnostic steps

1. 01

   Move goods and record code

   Transfer perishable goods to a cabinet at the correct temperature class and note the fault code and device serial number.

2. 02

   Locate the suction manifold sensor

   Identify the temperature probe clamped to or inserted in the suction manifold or suction line, per the AHT service diagram for your Vento variant.

3. 03

   Inspect sensor wiring

   Check the sensor lead and connector for cuts, pinching, or corrosion. Reseat the connector firmly; a poor contact is the most common cause.

4. 04

   Measure sensor resistance

   Disconnect the sensor and measure resistance with a multimeter at ambient temperature. Compare to the NTC curve in the AHT service manual; open or short circuit confirms sensor failure.

5. 05

   Replace sensor if defective

   Fit an AHT-approved replacement sensor, ensuring correct placement and secure mounting on the suction line.

6. 06

   Clear fault and verify

   Power up the cabinet and confirm E02 clears. Allow 2 hours of normal operation before reloading goods.

When to call a professional

Sensor replacement is a refrigeration service task. On R-290 (propane) units, any work near the refrigerant circuit requires technicians certified for flammable refrigerants. Contact AHT service at 00800/73783248 or www.aht.at/service to dispatch an authorized technician.