Thermador Oven: error code 43 during preheating
What is this symptom?
If your Thermador oven displays error code 43 during preheating, it indicates a fault detected by the control system, halting the preheat cycle. Common causes include cooling fan issues, temperature sensor failures, or control board malfunctions. Understanding these can help you troubleshoot effectively.
Important Tips for Thermador Models
- Thermador official error code documentation does not publicly list code 43, so detailed definitions come mainly from repair communities and expert discussions.
Possible Causes
Cooling fan fault or airflow detection failure
How to Identify: Error appears when fan doesn’t run or the airflow detection switch/sensor isn’t triggered during operation; visual inspection may show stuck fan blades or misaligned switch. Oven overheats internally without adequate cooling.
Part: Cooling fan / sail switch or Hall effect airflow sensor
Temperature sensor fault leading to safety shutdown
How to Identify: Oven heats then shuts off with code 43; temperature sensor resistance deviates significantly from ~1080 ohms at room temperature when tested with a multimeter.
Part: Oven temperature sensor (RTD/probe)
Control board or fan relay/control circuit failure
How to Identify: Cooling fan appears to run properly and temperature sensor tests normal, but code persists; checking relay output or power to fan may show control board isn’t activating fan correctly.
Part: Control board / fan relay circuit
DIY Solutions
Inspect and clean cooling fan and sensor/switch
- Turn off power to the oven and disconnect from mains.
- Remove the back panel to access the cooling fan assembly.
- Visually inspect the cooling fan for obstructions, debris, or stuck blades; clear any blockages.
- Check the sail switch or Hall effect airflow sensor alignment and reposition if misaligned per repair guidance.
- Reassemble and restore power, then test by initiating preheat cycle.
Temperature sensor resistance check and replacement
- Disconnect power to the oven.
- Locate the temperature sensor (usually inside the oven cavity mounted near the back wall).
- Disconnect and measure resistance at room temperature; compare against expected value (~1080 ohms).
- If resistance is significantly out of range, source the correct replacement sensor for your model and install it.
- Restore power and test oven preheat cycle.
Next step
Choose the next step for error code 43 during preheating
Confirm the diagnosis before ordering. An error code can identify the system involved, but it does not prove that a specific part has failed.
Most relevant component to inspect
Cooling Fan Motor
Moves cooling air around hot cooking components and electronic controls.
- Typical part-only price
- $35 - $120
- DIY difficulty
- Medium
- Estimated time
- 30-75 mins
Where can I find the model number?
Check the rating label around the door, lid, frame, rear panel, or inside the appliance cabinet. Use the complete model number, including suffixes.
Verify the complete model and part number on the retailer's compatibility page before ordering.
Other parts options
Check related components first; use model search as a fallback.
Temperature Sensor
Monitors the internal temperature to ensure correct operation and prevent overheating.
Main Control Board
The central brain of the appliance that controls all components, cycles, and timings.
Model-compatible Oven parts
Enter the complete model number to browse compatible replacement parts. This is a model-based parts search, not a diagnosis that a specific component failed.
Affiliate disclosure: As an Amazon Associate I earn from qualifying purchases. We may earn a commission from other qualifying purchases or service requests made through links on this page, at no additional cost to you. Recommendations are based on repair relevance, not commission rate.
Optional routine care
Maintenance supplies
These products support cleaning or routine upkeep. They are separate from the possible repair components above and are not claimed to fix this error code or symptom.
Non-Scratch Cooktop Cleaner
A routine surface-care product. Confirm that it is approved for the specific glass, ceramic, enamel, or stainless finish.
Oven Thermometer
A diagnostic aid for comparing cavity temperature during a controlled check. It does not prove which internal component has failed.
Affiliate disclosure: As an Amazon Associate I earn from qualifying purchases. Recommendations are based on routine-care relevance, not commission rate.
Professional Repairs
Replace cooling fan assembly or airflow detection components
Control board relay or main board repair/replacement
When to Call a Professional
Preventive Maintenance
-
Clean cooling fan and vents: Airflow obstruction issues that may trigger error codes
Frequency: every 6 months -
Inspect temperature sensor resistance periodically: Temperature sensor drift or failure
Frequency: annually
Frequently Asked Questions
Why is my Thermador Oven error code 43 during preheating?
How do I fix Thermador Oven error code 43 during preheating myself?
How much does it cost to fix error code 43 during preheating?
When should I call a technician for error code 43 during preheating?
References & Sources
- Thermador Oven Error Codes support page Official
- Thermador Range E43 Error - MD Appliance LLC Repair-Blog
Community Analytical Insights
Guidance from available sources; statistical claims are shown only for samples of at least 10 discussions
Common Issues Reported by Users
- Faulty temperature sensor
- Malfunctioning control board
- Wiring issues or loose connections
User Suggested Solutions
-
Check and replace the temperature sensor. To do this, unplug the oven, locate the temperature sensor (usually at the back of the oven cavity), disconnect it, and replace it with a new one. Reconnect and test the oven.
-
Inspect the control board for any visible damage or burnt components. If found, replace the control board. This may require removing the back panel of the oven. Ensure the oven is unplugged during this process.
-
Check all wiring and connections to ensure they are secure and undamaged. Look for any loose wires or burnt connectors. Tighten or replace as necessary.
Limited-source guidance; percentages and success-rate claims are not shown
View
Sources
Data compiled from real discussions on r/appliancerepair and r/Appliances:
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