Induction Cooktop Error Code vs Pan Fault Decision Tree

Why this matters

Induction cooktop "error" complaints split into two completely different categories: actual electronic faults requiring component replacement, and cookware-compatibility faults that look like errors but have no service path. The customer typically does not distinguish between the two and reports "the cooktop isn't working." Burning two hours on what turns out to be a stainless-clad-aluminum pan that lost its ferromagnetic base is the modal rookie failure on induction calls. The decision tree below qualifies the cookware in 60 seconds, then runs real faults to power-stage components, control board, or sensor failures.

Symptom presentation

Customer reports one or more burner zones showing an error icon (typically a "U", "F", or symbol) or simply not heating when a pot is placed on the zone. Probe questions:

• Does the error appear immediately on pot-place, or partway through cooking?
• Is the affected zone the same physical zone or any zone?
• Same pan across multiple zones, or multiple pans on the same zone?
• Recent change: new cookware, recent power event, recent oven self-clean (on a slide-in range with induction top), or unit moved/recently installed.

The first qualifying test: a known-good ferromagnetic pan (cast iron or branded-induction stainless) placed on the affected zone. A magnet sticks to the base = pan qualifies. If the cooktop heats this pan, the original complaint was a pan-compatibility issue. If the cooktop still errors with a qualified pan, the call is a real fault.

Quick checks (under 10 minutes)

• Magnet test on the customer's cookware. A neodymium magnet should stick firmly to the entire base, not just the edge. Stainless steel with aluminum core does not work; cast iron does; enameled cast iron does; pure aluminum does not; copper does not; glass does not.
• Pan base diameter vs zone minimum. Most induction zones require 4-5 inch minimum pan diameter for the zone to recognize the load. A small saucepan on an 8-inch zone reads "no pan" and shows a U-code.
• Pan base flatness. Warped pan bottoms lift off the cooktop surface and break the magnetic coupling. The cooktop reads no load and errors out.
• Cooling fan audible from underneath. Induction generates significant waste heat in the IGBT stage; a seized fan triggers thermal shutdown with a heat-related error code (typically E1 / E2 / F2 family across OEMs).
• Glass surface temperature. After 5 minutes of heating a qualified pan, the surrounding glass should be warm-to-hot but not searing. Severe local heating beyond the cooking zone suggests a coil-positioning fault or surface debris.

Isolation tree - Pan-side faults (resolve here without parts)

Branch P1 - Non-induction cookware. Magnet does not stick. Educate, recommend induction-compatible cookware, close the call as not a fault.

Branch P2 - Marginal cookware (stainless-clad). Magnet sticks weakly. Cooktop recognizes the load intermittently and may error mid-cook as the pan heats and the ferromagnetic phase shifts. Same answer: recommend dedicated induction cookware.

Branch P3 - Pan too small for zone. Magnet sticks, pan does not heat. Verify pan base diameter against zone minimum (see OEM use guide). Recommend smaller-zone use or larger pan.

Branch P4 - Warped pan base. Visible rocking on a flat surface. Replace pan; not a service call.

Isolation tree - Cooktop-side faults

Branch C1 - Thermal shutdown / cooling fan failure (~25%). Error code lights after 5-15 minutes of cooking. Fan does not run or runs slowly. Underside debris (cabinet dust, kitchen grease) clogs the fan intake. Clean intake and verify fan operation. Replace fan if seized - typical MSRP $40-80.

Branch C2 - Failed IGBT module (~20%). IGBT (insulated gate bipolar transistor) is the power-switching device in the induction power stage. Failure modes: shorted (zone heats uncontrolled or trips main breaker on power-up), open (zone does not heat, shows F or E code referencing power stage). Power-stage repair is at the level of individual IGBT replacement on the power board - field-repairable with soldering equipment and an oscilloscope, but most shops replace the power module assembly.

Branch C3 - Failed coil temperature sensor (~15%). Each induction coil has a thermistor sensing the underside of the glass over the coil. Open thermistor = board sees over-temperature and shuts down with a sensor-fault code (typically F03, F04, or similar - see OEM table). Ohm at room temperature against the OEM spec; commonly 10-20K at 75F.

Branch C4 - Failed user-interface / capacitive touch sensor (~15%). Touch sensor fails to register or registers ghost touches. Symptoms: zone turns off mid-cook, zone refuses to set, control lock activates spontaneously. UI assembly replacement, MSRP $150-400.

Branch C5 - Power supply fault (~10%). Cooktop has no display or one half of the cooktop is dead. Verify 240V at the supply terminal block. Internal SMPS feeding the control logic can fail and disable the entire cooktop. Replace power supply board.

Branch C6 - Main control board (~10%). Communication errors between UI and main board show as Cxx or comm error codes. Verify ribbon cable seating before condemning the board. Main board MSRP $300-600 across major OEMs.

Branch C7 - Cracked glass (~5%). Visible crack across the cooking surface. Cooktop may show error or may operate but is unsafe - cracked ceramic glass is a fire and shock hazard. Replace as a glass-and-coil-assembly unit on most platforms (the coil bonded under the glass means replacement is integrated).

Confirming diagnosis

• Pan compatibility: known-good cast iron pan substitution. Definitive.
• Cooling fan: audible verification, IR temperature check at the IGBT heatsink under the cooktop (should not exceed 200F during cooking).
• IGBT: scope across the gate-drive signal and observe switching waveform. No-switching = IGBT or gate driver. Without a scope, substitution of the power-board assembly is the field method.
• Coil sensor: two-point ohm check at room temperature and at known-warm temperature.
• UI / touch: OEM service mode test of each touch zone. Many platforms enter a self-test diagnostic via a code sequence; consult the tech sheet behind the back panel.
• Power supply: measured DC rails at the SMPS output, compared to OEM rail specs.
• Glass: visual inspection plus pressure test (firm press across the surface listening for clicking from the crack).

Remediation - repair vs replace ROI

References

• UL 858 Standard for Household Electric Ranges (includes induction cooktops)
• IEC 60335-2-9 (particular requirements for grills, toasters, and similar portable cooking appliances - induction cooktop test conditions)
• NEC 422 (appliance branch circuits and disconnects)
• DOE 10 CFR 430 Subpart B Appendix I1 (cooking products test procedure)
• Wolf Service Manual CT15I (induction cooktop diagnostic mode and fault code table)