Baxi Boiler E156 Fault Code: Causes, Fixes & What to Do Next
If your Baxi boiler is showing the E156 fault code, it usually points to a low voltage (under-voltage) issue typically when the supply drops below 195V. This fault prevents the boiler from running safely, and while sometimes it’s a quick fix, in other cases it needs a Gas Safe engineer’s attention.
In this guide, we’ll break down the common causes of the E156 fault, how to troubleshoot it, and when to call in professional help.
Table of contents
What Causes the E156 Fault on a Baxi Boiler?
The E156 code isn’t always down to the boiler itself it can often be linked to your home’s power supply. Here are the most likely causes:
1. Power Supply Issues
- Temporary power cuts or voltage drops from your mains supply.
- A tripped circuit breaker stopping stable power from reaching the boiler.
- Fluctuations in household electricity, especially in older properties.
2. Transformer Fault
The boiler’s internal transformer is responsible for regulating voltage. If it’s faulty, it may fail to supply the correct power levels to key components.
3. Wiring Problems
- Loose or damaged internal wiring inside the boiler.
- Poor or unstable connection from the external power supply.
4. Internal Component Failure
In rare cases, the E156 code can be triggered by failing parts such as:
- The gas valve
- The spark igniter
- The pump
How to Fix the Baxi Boiler E156 Fault Code
Time needed: 5 minutes
Before calling out an engineer, there are a few basic checks you can safely carry out:
- Check the Mains Supply
Make sure your home has power and the boiler’s circuit breaker hasn’t tripped. If other electrical appliances are flickering or tripping, it could point to a wider voltage problem.
- Reset the Boiler
Try resetting the boiler using the front panel reset button (if fitted). Switch the boiler off, wait 30 seconds, then turn it back on.
- Look for Other Fault Codes
Sometimes E156 appears alongside another error. Deal with any other fault codes first, as they may be contributing to the low voltage issue.
- Call a Gas Safe Engineer
If the problem continues after trying these steps, do not attempt to open or repair the boiler yourself. Instead, contact a Gas Safe registered engineer who can safely inspect the appliance, test the transformer and wiring, replace any faulty components if needed, and ensure the boiler is operating safely and correctly.
Conclusion
The Baxi boiler E156 fault code signals that your boiler is struggling with low voltage. In many cases, it’s as simple as a tripped breaker or a temporary power dip. But if the issue persists, it could be linked to wiring faults, a bad transformer, or failing internal components.
Frequently Asked Questions
The error code relates “Under voltage (lower than 195V) has been supplied to boiler, where you are not experiencing power issues this suggests the circuit boar din the boiler has failed and not able to regulate the power properly, s would need a Gas Safe engineer to attend if you have already powered the boiler off for
Description: The E156 error code often occurs due to a problem with the electrical supply to the boiler. This could be due to a power cut, a faulty circuit breaker, or issues within the home’s wiring. Solution: Check the mains supply and ensure the circuit breaker has not tripped.
If your Baxi boiler displays an E168 error, you should first check the water pressure to ensure that it is at the correct level. If the water pressure is fine, you should then check the other components of your boiler, such as the sensors and thermostats, to ensure that they are functioning properly.
