What Er42 Means
Er42 means the control board's internal 5-volt logic supply — the low-voltage rail powering its own electronics — is reading outside its valid range or fluctuating more than allowed, and that can produce erratic behavior across the whole cooktop.
Common Causes of Er42
- A failing power-supply part on the control board
- A loose or corroded connector disrupting the low-voltage circuit
- A general failure of the control board
🔧 One Safe Check You Can Try
No safe DIY test exists — confirming a 5V supply problem takes a multimeter and a de-energized unit, technician work through and through.
⚠ Why You Shouldn't Go Further Than That
- Because this problem sits in the board's own internal power supply, testing it live risks both a misleading reading and a shock.
- An unstable 5V rail can make the board act unpredictably across several zones at once, which makes self-diagnosis unreliable.
- Treat this as a single-zone or single-sensor issue and you'll pay for the wrong, too-narrow repair.
- The top is bedded on a foam strip that seals it to the worktop, and that strip tears coming up, so the cooktop no longer sits sealed against spills afterwards.
Opening a panel to inspect or repair something yourself doesn't automatically cancel your manufacturer's warranty — but it can risk accidental damage, and some manufacturers do have specific service conditions. Check your product's warranty terms, or ask us, before deciding.