Thermador Oven Error Code E340: How to Fix It

Q: Is it safe to use my Thermador oven for baking while the E340 error is showing?

The main oven cavity may still function when E340 is active, but the warming drawer will be disabled or unreliable. It is generally safe to use the primary oven functions, but you should not rely on the warming drawer until the fault is resolved, as the thermistor fault means the drawer's temperature is not being properly monitored.

Q: How much does it cost to fix Thermador oven error E340?

If the fix is a thermistor replacement, parts typically cost between $20 and $60 depending on the model. If professional labor is involved, expect an additional $100–$200 for a service call and repair. A control board replacement can cost $150–$400 or more for the part alone, making professional diagnosis worthwhile before purchasing one.

Q: Where is the thermistor located on a Thermador warming drawer?

The warming drawer thermistor is usually mounted on the interior wall of the warming drawer cavity — the space the drawer slides into — rather than on the drawer itself. It is a small sensor held by one or two screws with a thin wire harness running back to the control board. Pull the drawer fully out to access it.

Q: Can a loose wire cause the Thermador E340 error code?

Yes. A loose or corroded connector between the thermistor and the control board is a very common cause of E340. The control board interprets a missing or intermittent signal the same way it interprets a failed thermistor. Always inspect and reseat all connectors before ordering replacement parts.

Q: Will the E340 error code clear itself after I replace the thermistor?

In most cases, once the faulty thermistor is replaced and the oven is powered back on, the E340 code will clear automatically when the control board receives a valid resistance reading from the new sensor. If the code persists after replacement, double-check the connector seating and inspect the wiring harness for additional damage.

Abstract

The Thermador oven error code E340 indicates a fault with the warming drawer thermistor — a small temperature-sensing component that monitors the heat level inside the warming drawer. When the oven's control board detects an abnormal reading from this thermistor (either a short circuit, open circuit, or out-of-range resistance), it triggers E340 and disables the warming drawer to prevent overheating. In many cases, this error is caused by a failed thermistor, a loose or corroded wiring connection, or — less commonly — a faulty control board.