What 3221 Means
Wolf's M Series Troubleshooting Manual lists 3221 as the upper cavity's RTD reading open circuit and 3222 as the lower, both priority 2. The control sends current through the sensor and nothing comes back - electrically identical to the sensor being unplugged, which is one of the possibilities.
Common Causes of 3221
- An RTD element that has gone open internally, a normal end-of-life failure
- A sensor plug that has backed out of its connector behind the rear panel
- A harness conductor broken where it runs through the cavity insulation
🔧 One Safe Check You Can Try
Note the failure pattern: an oven that refuses to start heating at all, versus one that quits part-way through preheat. Both fit an open sensor but they point at different places in the circuit.
⚠ Why You Shouldn't Go Further Than That
- Reaching the sensor connector means the rear panel, where the oven's supply lands on a terminal block.
- An open reading at the board does not say whether the break is in the probe, the plug or the wire, and only measurement at both ends settles that.
- Built-in ovens are heavy and awkward to draw out of cabinetry, and damaged surrounds cost more to put right than the sensor did.
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.