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Difficulty: MediumTroubleshooting and Error Correction Steps

An audio maintenance guide provides the following troubleshooting instructions for a commercial espresso machine displaying error code E-04:

'When error code E-04 is displayed, first close the primary steam valve and wait until the pressure gauge falls below 0.5 bar before opening the drainage port. After draining the chamber, flush the intake filter, ensuring that the digital pressure transducer mounted above the valve is kept completely dry. Finally, reassemble the components and execute a five-minute diagnostic cycle in purge mode.'

Based on the audio instructions, which of the following is the correct procedure for troubleshooting this error?

  1. A
    Execute the five-minute diagnostic purge cycle before closing the primary steam valve and opening the drainage port.
  2. B
    Submerge both the digital pressure transducer and the intake filter completely in cleaning liquid to clear the fault.
  3. Close the primary steam valve, wait for the pressure to drop below 0.5 bar before opening the drainage port, clean the filter keeping the transducer dry, and run a purge diagnostic.Answer
  4. D
    Open the drainage port immediately while the primary steam valve remains active to rapidly release residual pressure.

Answer

Close the primary steam valve, wait for the pressure to drop below 0.5 bar before opening the drainage port, clean the filter keeping the transducer dry, and run a purge diagnostic.
The correct response accurately synthesizes all three phases of the troubleshooting protocol: the initial shut-off and pressure threshold check (<0.5 bar), the selective cleaning constraint (keeping the transducer dry), and the concluding diagnostic purge cycle.

Step-by-Step Solution

1
Identify the initial safety and preparatory actions from the audio
The technician must first close the steam valve and verify that pressure drops below 0.5 bar before opening the drainage port.
Prevents injury and system damage before accessing internal liquid chambers.
2
Analyze component-level cleaning constraints
The intake filter must be flushed while keeping the digital pressure transducer dry.
Ensures adherence to specific negative constraints and prohibitions stated in the guide.
3
Confirm the final verification step in the sequence
Reassemble the unit and execute a five-minute diagnostic cycle in purge mode.
Validates system recovery after completing physical maintenance.

Key Concept

Sequencing and constraint verification in multi-step technical troubleshooting
Estimated Time:1m 15s
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Topics

Troubleshooting and Error Correction Steps

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