GE Wall Oven Repair in Toronto — Oven temperature inaccurate

• Drifted oven sensor (RTD WB21X5301) is the #1 cause of a GE oven that bakes hot or cold. The sensor is a platinum resistive temperature device (RTD) that should read about 1080-1100 ohms at room temperature (~1100 ohms at 77F); as the coil ages its resistance wanders out of spec, so the control 'thinks' the cavity is a different temperature than it really is. We meter it cold against the GE RTD curve - roughly 1000 ohms at 0C, ~1100 at 25C, ~1450-1465 at 121C, ~1650-1675 at 177C, climbing about 2 ohms per degF (so ~1580 at 350F) - and anything off the curve means the WB21X5301 gets replaced, not recalibrated.
• F3 on a GE oven flags a fault in the temperature-sensor circuit - typically an open/failed RTD, though across GE control generations the codes split (F3 commonly = open, F4 = shorted, and some controls label one code 'shorted or open'). On a temp-inaccurate complaint it surfaces as wild swings or a cavity that won't hold setpoint before it faults out. Before we condemn the WB21X5301 we always check the sensor harness and the plug where it lands on the control, because a broken sensor and a disconnected/corroded lead read identically on the display.
• F2/F20 is the runaway-heat / overheat code and it masquerades as 'my oven runs way too hot.' GE trips it above ~650F (343C) in normal bake and above ~915F (491C) in self-clean. The honest split: either the RTD/harness is feeding a FALSE high reading, or the oven is genuinely overheating because a relay on the control board welded shut and is sending continuous voltage to the bake element (a clogged self-clean vent can also drive an overheat). We never reset-and-return an F2 - an uncontrolled-heat GE is a fire risk until the cause is proven.
• A corroded or loose sensor-harness connection is its own temp-inaccuracy fault, separate from the sensor itself. Added resistance in that circuit stacks onto the RTD's reading, so the control sees a higher number than the real cavity temp and under-heats the food (or, on the high side, false-trips F2). On GE we clean and re-seat that connector and re-meter end-to-end before anyone buys a WB21X5301 - it's a frequent false-positive on sensor swaps.
• When the bake relay on the GE control board (ERC, WB27T-family - e.g. WB27T11311 / WB27T10265 / WB27T10406 depending on model) welds closed, the element gets power it shouldn't and the cavity genuinely overheats - the real, dangerous version of 'temp inaccurate.' We inspect the bake/broil relay contacts on the board; welded contacts mean the board is the fix, and a true overheat event also warrants checking whether the safety/thermal cut-off already reacted.
• Built-in OFSt calibration is the first thing we rule in or out: on GE you hold Bake + Broil ~3 seconds to reach the OFSt offset and trim only +/-35F (it adjusts bake and does not touch broil or self-clean temps). If a verified-thermometer test shows the oven off by MORE than 35F, calibration physically cannot fix it - that points to a failed RTD (WB21X5301) or the control board, not to a 'setting.' We bring a calibrated oven thermometer to separate a real fault from an in-range offset.
• Sensor placement and probe condition cause a subset of 'inaccurate' GE calls: an RTD bent against the rear wall or touching a rack/element reads localized heat instead of cavity air, so the bake side over- or under-shoots even with a healthy WB21X5301. We verify the sensor sits proud off the back wall (2 screws) and isn't shorting to metal before changing parts.

GE oven temperature inaccurate in Toronto — the local specifics

• The recurring GE-in-Toronto pattern for temp-inaccurate is a hot/cold bake traced to a drifted WB21X5301 RTD - and a steady minority where the real fault is the harness connector, not the sensor, so a meter-and-reseat saves the customer a needless part. The dangerous tail of this symptom is F2/F20 overheat from a welded control-board relay, which we treat as do-not-use until proven.
• We carry the GE WB21X5301 oven sensor and a calibrated oven thermometer to every temp-inaccurate GE call, plus harness-cleaning tools to test the sensor circuit end-to-end before swapping parts. WB27T-family control boards we confirm by model and order through the local distributor when the board (welded relay) is the real cause rather than the sensor.

For the full GE wall oven module — every fault, part number and code — see GE wall oven repair in Toronto, and for the same fault across all brands the wall oven oven temperature inaccurate guide.