Worcester Bosch Fault Codes
Our Worcester Accredited Engineers are here to help you understand what each fault code means, and what steps to take next.
Worcester Bosch Fault Codes
Understanding Your Worcester Bosch Boiler's Fault Codes
If your Worcester Bosch boiler is displaying a fault code, our Worcester Bosch Accredited engineers across Bedfordshire and Hertfordshire are on hand to help. Below you'll find a guide to the most common fault codes, what they mean, and what to do next, so you can get your heating and hot water back up and running with confidence.
Worcester Bosch Fault Code List
Below is a complete list of Worcester Bosch fault codes and what is causing them
Ignition & flame faults
What's going on?
Your boiler has tried to light but hasn't been able to detect a flame, or has lost the flame partway through firing. This is usually down to a gas supply issue, a worn or faulty ignition electrode, or a blocked flue restricting the boiler's air supply.
What should you do?
Check that your gas supply is switched on and that other gas appliances in your home are working, then try resetting the boiler once. If the fault comes back, it's a sign of an underlying issue that needs a Worcester Bosch Accredited engineer to diagnose safely.
What's going on?
The boiler has picked up a flame signal before the burner has actually started, which usually points to a fault with the ignition electrode wrongly sensing a flame.
What should you do?
This isn't something to attempt yourself. It needs a Worcester Bosch Accredited engineer to check the electrode and wiring before the boiler is used again.
What's going on?
The boiler has detected a flame signal after the gas valve has already closed. This can mean the gas valve isn't sealing properly or there's a fault with the ignition electrode.
What should you do?
This is a safety-critical fault, so please don't try to reset or bypass it. Turn the boiler off and call a Worcester Bosch Accredited engineer to inspect the gas valve straight away.
Overheat & safety cut-out faults
What's going on?
Your boiler has detected it's running hotter than it should and has shut itself down as a safety precaution. This can be caused by restricted water flow, a failing pump, or a blocked heat exchanger.
What should you do?
Don't keep resetting the boiler if this fault repeats, as it's a safety feature doing its job. A Worcester Bosch Accredited engineer will need to find out why the boiler is overheating before it's used again.
Sensor faults
What's going on?
The sensor that measures the temperature of the water flowing from your boiler has developed a fault, either from a short circuit or a loose connection.
What should you do?
This needs a Worcester Bosch Accredited engineer to test and, if needed, replace the sensor.
What's going on?
The sensor that monitors the water returning to your boiler has developed a fault, similar to the flow sensor but on the return side of the system.
What should you do?
An engineer visit is needed to test the sensor and its wiring and replace it if faulty.
What's going on?
Your boiler has picked up that the water temperature is climbing too quickly, which can point to a restriction in the heat exchanger or an issue with one of the temperature sensors.
What should you do?
This one needs a closer look from a Worcester Bosch Accredited engineer to find out what's causing the rapid rise before any damage occurs.
Fan faults
What's going on?
The boiler's fan is running outside of its normal speed range. In colder months this can be linked to a frozen or blocked condensate pipe, but it can also point to a fan fault.
What should you do?
If you can see the condensate pipe outside and it's frozen, gently warming it may clear the fault. If that doesn't work, or you can't access the pipe safely, an engineer will need to check the fan.
What's going on?
The boiler's fan isn't running at all when it should be, which points to a fault with the fan itself rather than a blockage.
What should you do?
This needs a Worcester Bosch Accredited engineer to inspect and replace the fan if necessary.
Pressure faults
What's going on?
Your boiler's system pressure has dropped below the level it needs to run properly, usually gauged as under 1 bar on the display.
What should you do?
This one you can usually sort yourself. Use the filling loop to top the pressure back up to around 1 to 1.5 bar. If it keeps dropping after topping up, there may be a leak, and it's worth getting an engineer to take a look.
What's going on?
The boiler's fan isn't running at all when it should be, which points to a fault with the fan itself rather than a blockage.
What should you do?
This needs a Worcester Bosch Accredited engineer to inspect and replace the fan if necessary.
Pump faults
What's going on?
The boiler's pump has either seized up or is running without enough water passing through it, often due to trapped air in the system or low pressure.
What should you do?
Check your system pressure first, as low pressure can trigger this fault. If pressure is fine and the fault persists, the pump itself likely needs an engineer's attention.
Internal / PCB faults
What's going on?
The boiler's control board has flagged an internal fault, which can be a software glitch or a hardware issue with the board itself.
What should you do?
An engineer will need to inspect the control board, and in some cases reset or replace it.
What's going on?
The boiler can't detect its code plug, the small component that tells the control board which model settings to use. This can mean the plug has come loose, failed, or there's a fault with the board.
What should you do?
This needs a Worcester Bosch Accredited engineer to check the code plug and connections.
Communication faults
What's going on?
Your boiler has lost its wireless connection to your room thermostat, so it isn't receiving instructions properly.
What should you do?
Check the batteries in your thermostat and make sure nothing is blocking the signal between it and the receiver. Re-pairing the two devices often clears this fault. If it continues, an engineer can check the signal strength and wiring.
What's going on?
The boiler has lost communication over its EMS-Bus connection, which links it to controls and accessories. This is often down to a loose or damaged cable.
What should you do?
Check the EMS-Bus cable connections if you're comfortable doing so. If the fault remains, an engineer will need to check the wiring and connected accessories.
What To Do When Your Boiler Shows A Fault Code
A few simple checks before you call for help
Before booking an engineer, a couple of quick checks can sometimes clear a Worcester Bosch fault code:
- Note down the exact fault code shown on the display
- Check your system pressure is within the normal range
- Make sure outside vents and the condensate pipe aren't blocked or frozen
- Try resetting the boiler once, if it's safe to do so
If the fault code returns, it's best to stop there and call a Worcester Bosch Accredited engineer.
Worcester Bosch Accredited Partners
Trained By Worcester Bosch, Trusted By You
As Worcester Bosch Accredited Partners, our Gas Safe registered engineers are trained directly by Worcester Bosch to install, service, and repair their boilers to manufacturer standards. This means faster, more accurate fault diagnosis and the ability to offer extended warranties on new installations.
When To Call An Engineer
Know when it's time to get the experts in.
Get in touch with us if:
- The same fault code keeps returning after a reset
- You've lost heating or hot water completely
- There's a leak around the boiler or pipework
- Your boiler shows a flame or overheating related fault code
If you ever smell gas, turn off your gas supply at the meter and call the National Gas Emergency Service on 0800 111 999 straight away, then contact us once it's safe.
You can also take a look at what our boiler repairs service covers before you get in touch.
Areas We Cover for Worcester Bosch Fault Code Repairs
No matter where you are in Bedfordshire or Hertfordshire, our Worcester Bosch Accredited engineers are on hand to diagnose fault codes and get your boiler back up and running.
