Your Baxi boiler showing the E20 error code means the system has detected an issue with a temperature sensor and has safely shut down to prevent damage or unsafe operation. This common fault often leaves homeowners and landlords without reliable heating or hot water until it is sorted.
What Does the Baxi Boiler e20 Error Code Mean?
The Baxi boiler E20 error code means there is a fault with the central heating NTC thermistor or primary temperature sensor. This small but important part measures the water temperature inside your boiler. When it sends the wrong signal or stops working properly, the boiler locks out as a safety measure. You will usually see no heating or hot water until the issue is resolved.
Many people notice this code after a cold snap or when the boiler has been working hard. It is the boiler’s way of telling you something needs attention before things get worse.
What Causes the e20 Error Code On Your Baxi Boiler?
The E20 error code on your Baxi boiler is most often triggered by problems with the temperature sensor or the connections that link it to the control system. Other factors like system pressure or electrical issues can play a part too. Understanding the root cause helps you decide the best next step.
Faulty Temperature Sensor or NTC Thermistor
A faulty temperature sensor, also called an NTC thermistor, is the most frequent reason for the E20 code. This little component sits on the flow pipe and constantly checks how hot the water is. Over years of heating cycles, it can wear out, get corroded by moisture, or simply stop giving accurate readings. Hard water areas in the UK can speed this up with limescale buildup.
When the sensor fails, the boiler cannot safely control the temperature and shuts down to avoid risks like overheating.
How to Fix
- Try a simple reset first by turning the selector switch to the reset position (often marked R) and holding it for a few seconds. Watch to see if the code clears and the boiler restarts normally.
- Check your system pressure gauge. If it is too low, top it up carefully following your manual instructions.
- If the fault returns quickly, call a Gas Safe registered engineer. They will test the sensor with proper tools and replace it if needed. This is a relatively straightforward job for a professional.
- Once fixed, run the heating to confirm everything works smoothly and monitor for any return of the error.
Wiring or Connection Problems
Loose, damaged, or corroded wiring between the sensor and the boiler’s control board can cause the E20 error code. Vibrations from the boiler, damp conditions in the cupboard, or even pests can affect the connections over time.
Poor contact means the boiler receives inconsistent or no signal from the sensor, triggering the safety lockout.
How to Fix
- Turn off the boiler at the isolator switch and let it cool completely for safety.
- Visually inspect any accessible wires near the boiler for obvious damage, frays, or loose plugs. Do not pull hard or attempt internal repairs yourself.
- Contact a qualified Gas Safe engineer to properly check and repair or replace any faulty wiring.
- After repairs, reset the boiler and test the heating system to make sure the error does not come back.
Other System Issues Like Low Pressure or Blockages
Sometimes the E20 fault code appears alongside low water pressure, air in the system, or poor water flow through the heat exchanger. These problems can make the sensor readings seem off even if the sensor itself is fine.
Low pressure is especially common in older systems or after bleeding radiators.
How to Fix
- Check the pressure gauge on your boiler. It should normally sit between 1 and 1.5 bar when cold.
- If low, repressurise using the filling loop (usually two flexible hoses underneath the boiler) slowly until the gauge reaches the right level.
- Bleed your radiators to remove trapped air if the system feels uneven.
- If pressure keeps dropping or the fault persists, have a Gas Safe engineer inspect for leaks, blockages, or pump issues.
Persistent error codes like the Baxi E20 can signal deeper wear in your heating system. At Eazy Heat, we often advise UK landlords and homeowners that upgrading to a modern, energy efficient boiler can cut long term repair bills and improve reliability, especially with current demands on home heating.
When Should You Call a Professional for Your Baxi Boiler E20 Error?
While a quick reset or pressure top up might clear the code temporarily, most E20 faults need professional diagnosis. Gas Safe registered engineers have the training and equipment to safely test components and make lasting repairs. Attempting complex fixes yourself risks voiding warranties or creating safety issues.
How to Prevent Future E20 Errors On Your Baxi Boiler
Regular servicing is the best way to avoid sensor faults and other issues. An annual check by a qualified engineer keeps your system clean, correctly pressured, and running efficiently. In hard water areas, consider a scale reducer or inhibitor to protect components.
UK statistics show that well maintained boilers last longer and use less energy, which helps with rising household bills. Many properties we support at Eazy Heat see significant savings after a full service or upgrade.
Upgrade to Reliable Heating with a New Boiler from Eazy Heat
If your Baxi boiler E20 error code keeps returning, it could be a sign that ageing components are becoming less reliable. Although replacing a faulty temperature sensor may resolve the immediate issue, recurring faults often indicate that your boiler is becoming more expensive to maintain. Frequent breakdowns, rising repair costs, and unexpected heating outages can all make replacing your boiler the more cost-effective long-term solution.
At Eazy Heat, we provide hassle-free new boiler installations for homeowners and landlords throughout the UK. Our experienced team makes the entire process simple, from providing a clear online quote to completing a professional installation. Every new boiler we install is backed by a market-leading 12-year parts and labour warranty, giving you complete confidence in your investment.
If you’re ready to enjoy dependable, energy-efficient heating without the worry of recurring boiler faults, use our online quotation tool today. In just a few simple steps, you’ll receive a transparent price for your boiler replacement and be one step closer to a warmer, more reliable home.
FAQs
Can I keep using my boiler with the E20 error code showing?
It is not recommended. The boiler has locked out for safety reasons. Continuing without fixing the underlying issue could lead to bigger problems or leave you without heating when you need it most. Always arrange a professional check promptly.
How much does it cost to fix a Baxi E20 error?
Repair costs typically range from £100 to £250 depending on whether a sensor replacement or wiring fix is needed. A full quote from a Gas Safe engineer gives the clearest picture for your specific boiler model.
Is the E20 fault covered under my boiler warranty?
It depends on the age of your boiler and whether it has been serviced regularly. Many Baxi warranties cover parts like sensors, but labour or call out fees may apply. Check your documentation or speak to the manufacturer.
Will a new boiler stop E20 type errors from happening?
Modern boilers have improved sensors and diagnostics, so faults are less common. Combined with proper installation and regular servicing, a new system from Eazy Heat significantly reduces the chance of recurring issues.
What other Baxi error codes should I watch out for?
Common ones include E28 (flue or another sensor issue), E110 (overheat), and E119 (low pressure). If your boiler shows any repeated codes, it is wise to get it checked to prevent escalation. Our team at Eazy Heat can advise during a quote consultation.