AEG Dryer Error EHO (EH0): Power Supply or Control Board Fault Diagnosis

User question

aeg error eho

Artificial Intelligence Response

Direct answer to the question

• On AEG appliances, error EHO (often shown as EH0) indicates a power-supply problem or an internal low‑voltage power supply (control board) fault. It is not a heat‑pump/refrigerant error.
• Key points:
  • Most common causes: loose/damaged plug or socket, extension/multi‑plug use, undersized/long wiring causing voltage drop, unstable mains, tripping RCD/AFCI, or a failing control‑board SMPS/zero‑cross circuit.
  • If EHO persists on a known‑good outlet, the main PCB’s power supply or sensing network is the prime suspect.

Detailed problem analysis

• What the appliance is detecting:
  • The control electronics monitor low‑voltage rails (typically 3.3/5/12 V) and the mains “zero‑cross” signal. If the rails brown‑out or the zero‑cross becomes erratic (due to sagging supply, bad connections, or a weak SMPS), the firmware raises EHO/EH0.
• When EHO appears:
  • Immediately at power‑up: often a weak control‑board SMPS (failed fusible resistor, LNK/TNY switcher IC, dried primary bulk capacitor, cracked solder joints) or a marginal outlet.
  • When a heavy load starts (heater, motor, or compressor on heat‑pump dryers): line sag from poor wiring/extension leads or a bad outlet causes the board to dip and throw EHO.
  • Sporadically mid‑cycle: intermittent neutral/earth connections, failing EMI filter, or vibration‑sensitive dry joints on the PCB.
• Why “heat‑pump fault” is not correct:
  • A blocked condenser or refrigerant issue affects drying performance/temperature but does not directly generate EHO. EHO is raised by electrical supply/logic supply anomalies, not by the sealed refrigeration circuit.

Current information and trends

• Manufacturer guidance for AEG/Electrolux lists EHO/EH0 as a power‑supply related error, advising to avoid extension leads, verify the wall socket/circuit, and seek service if the issue persists on a good supply.
• Field experience: a significant share of persistent EHO cases are resolved by repairing/replacing the main control module due to failed primary‑side components or cracked solder joints.

Supporting explanations and details

• Typical internal failure modes on the main PCB:
  • Open/shifted fusible resistor (≈33–100 Ω) in the SMPS input.
  • Failed LNK/TNY (or similar) flyback switcher IC.
  • High‑ESR or low‑capacitance primary bulk capacitor (e.g., 6.8–22 µF/400 V).
  • Cracked joints on power relays/triacs and the mains input terminal block.
  • Drifted high‑value resistors in the zero‑cross divider; bad optocoupler.
• Visible/audible clues:
  • Repeated relay “clicks” or display resets when a load energizes indicate brown‑out.
  • Discolored plug pins, warm outlet faceplate, or scorch marks point to high contact resistance.

Ethical and legal aspects

• Safety first: diagnosing inside the appliance exposes live mains and charged capacitors. Only a qualified person should perform energized tests or component‑level PCB work.
• In many jurisdictions, refrigerant systems and hard‑wired circuits require certified technicians; however, EHO diagnosis should focus on electrical supply and control electronics.

Practical guidelines

User‑safe checks (no tools or only a simple multimeter):

1. Power path sanity check
   • Plug directly into a fixed, dedicated wall outlet; do not use extension cords, adapters, or power strips.
   • Reseat the plug fully; inspect for heat discoloration or looseness.
   • Try a different known‑good outlet on a different circuit. If EHO disappears, the original outlet/circuit is suspect.
2. Load test the outlet/circuit
   • On the same outlet, run a high‑load device (e.g., space heater or kettle). Watch for flicker, tripping, or warmth at the outlet—signs of a weak connection.
3. Basic reset
   • Power off, unplug for 1–5 minutes, then retry a short program.
4. Environmental/electrical context
   • In the US, ensure the dryer is on the correct 240 V circuit (not a 120 V receptacle via adapter). Shared circuits with large loads (HVAC, EV charger) can cause sag and EHO.

Technician‑level checks (competent with mains work):

1. Measure supply under load
   • Record line voltage at the outlet: no‑load and when heater/compressor engages. A sag >10% (e.g., below ~207 V on a 230 V appliance or below ~216 V line‑to‑line on a nominal 240 V circuit) can trigger EHO.
2. Inspect mains input and wiring inside the appliance
   • Terminal block tightness, spade connectors, EMI/RFI filter integrity, signs of heat.
3. Control‑board diagnostics
   • Check the primary fusible resistor, input rectifier, bulk capacitor ESR/capacitance, SMPS switcher IC, optocoupler, and zero‑cross network. Reflow relay pins and high‑current joints.
   • Verify secondary rails (e.g., 5 V) for stability during load transitions; scope preferred.
4. If board is beyond repair
   • Replace with the exact part number and apply any firmware configuration steps prescribed for the model.

Possible disclaimers or additional notes

• If EHO appears only in one room or on one branch circuit, the building wiring or breaker may be at fault; involve a licensed electrician.
• Some units may intermittently clear after a reset; this usually recurs unless the root cause (supply or PCB) is corrected.

Suggestions for further research

• Obtain the service manual for your exact AEG model to locate test points, nominal rail voltages, and error‑tree procedures.
• If board repair is intended, consult the PCB schematic/parts list (when available) or create a reverse‑engineered diagram focusing on the SMPS and zero‑cross sections.

Brief summary

• EH0/EHO on AEG means the appliance detects an unstable or incorrect power supply or a failing control‑board power/sensing circuit—not a heat‑pump fault.
• First rule out the outlet, circuit, and any extensions; then suspect the control board SMPS/zero‑cross hardware.
• If it persists on a known‑good socket, plan for PCB repair or replacement.

If you share your exact model number, where/when the error appears (immediately, at heater/compressor start, or randomly), and what power outlet/circuit you’re using, I can tailor a step‑by‑step test plan and, if you’re comfortable with electronics, a component‑level checklist for your board.

Disclaimer: The responses provided by artificial intelligence (language model) may be inaccurate and misleading. Elektroda is not responsible for the accuracy, reliability, or completeness of the presented information. All responses should be verified by the user.