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The Worcester E6 error indicates a fault with the hot water sensor in your boiler-an essential component that helps maintain safe and consistent hot water temperatures. If your Worcester boiler is showing E6, it means the system can’t accurately read the temperature of the domestic hot water, and for safety, it locks out or reduces functionality. The E6 error is commonly found in premium models such as the Bosch CDI Classic Combi and the cdi classic combi boiler, both known for their high performance, reliability, and advanced features. At 0800 Homefix, we regularly resolve these faults quickly and professionally.
This guide explains what causes the Worcester Bosch E6 fault code, how to troubleshoot it, and when to call for expert help.
What Does the Worcester E6 Error Code Mean?
The E6 on Worcester boilers typically signals a defective or disconnected domestic hot water temperature sensor. This sensor, often a Negative Thermistor Coefficient (NTC) thermistor, monitors water temperature and communicates it to the boiler’s control unit. If it fails, the boiler may:
Stop producing hot water
Run water too hot or cold
Shut down entirely with an error message like:
Worcester Bosch E6 fault code
E6 hot water fault Worcester
Worcester boiler showing E6
Worcester boiler error codes, such as the E6, are key diagnostic tools for identifying faults in models like the classic combi boiler. Understanding the Worcester Bosch error code system helps with troubleshooting and resolving issues quickly.
Without a functioning sensor, the boiler can’t guarantee safe operation. This error is one of several combi boiler error codes and may also appear alongside others related to the flow temperature sensor, flue gas thermostat, or pressure sensor.
Signs of a Hot Water Temperature Sensor Issue in Worcester Boilers
If your boiler displays the E6 fault, you might also notice:
Water taking too long to heat up
Inconsistent hot water temperature
No hot water at all, even when heating is on
Display error fluctuating with temperature demand
Burner briefly lights then cuts out (possible ionisation detected after ignition)
These symptoms often indicate issues with the domestic hot water (DHW) system, which relies on accurate sensor readings for safe operation.
This points directly to a hot water sensor issue in Worcester boilers or a miscommunication with the ignition burner control unit.
Common Causes of E6 Hot Water Fault and Combi Boiler Error Codes in Worcester
The E6 error may be triggered by several issues:
Sensor degradation or a temperature sensor defective due to age or limescale
Thermistor coefficient NTC defect or short circuit in the wiring
Incorrect code plug detected by the control module; ensure the correct code plug is installed to avoid compatibility errors
Flue gas thermostat overheat protection tripping
Faults in the heat exchanger temperature sensor, and ensure the flow temperature sensor correctly is checked, connected, or replaced if necessary
Pressure sensor defective; during diagnostics, always check pressure sensor connection and perform pressure sensor replace if faulty
Signal faults in the gas valve relay, gas valve EV1 leak, gas valve EV2 leak, gas valve leak, or EV1 leak test failed; perform a valve EV1 leak test during troubleshooting
Flame detected after gas or detected after gas shut are safety-related error conditions; monitor the flame signal for proper operation
Damaged cable exchange fuse, incorrect installation position
Operation at minimum burner load can relate to system combi boiler error codes
Possible faults in the heat control module; also check the integrity flue system and outside temperature sensor for defects
Monitor flow temperature rise to prevent rapid temperature changes and system strain
These problems are especially common in models such as the Worcester Bosch CDI Compact, CDI Classic Combi, Bosch CDI Classic Regular, cdi classic regular boiler, and Greenstar i System Combi.
Troubleshooting the Worcester Bosch E6 Fault Code
If you’re confident with basic boiler checks:
Reset the Boiler: Some internal faults may clear after a reboot.
Check Hot Water Flow: Monitor taps for delay or poor temperature.
Review Boiler Display: Look for secondary errors like flow temperature rising, temperature difference greater, or central heating boil detected.
Do Not Attempt Internal Testing: Issues like flow and safety sensor or CH flow NTC sensor faults must be handled by professionals.
⚠️ Never tamper with the gas supply, modulating gas valve, or interconnected room air supply. These affect combustion and safety limits.
How 0800 Homefix Can Help
At 0800 Homefix, we address more than just the sensor itself. Our engineers can test and resolve faults in related components, including:
Hot water temperature sensor and flow temperature sensor
Thermistor Coefficient NTC Sensor communication
Pressure sensor connection and pressure sensor replacement
Diagnostic of the control module HCM error or internal error conditions
Checking for valve EV2 leak test failures and safety temperature limiter malfunctions
We service all Worcester boilers, from CDI Classic Regular Boilers to Bosch Greenstar i System models.
How to Prevent Worcester Hot Water Sensor Issues
Book annual boiler servicing to test components like the NTC sensor and flue gas thermostat
Prevent temperature limiter in central heating from tripping due to overheating
Keep system pressure in range and avoid pressure drop that may affect boiler logic
Install a water softener in hard water areas to reduce sensor wear from scale
By maintaining the temperature sensor and checking the gas valve regularly, you can reduce the risk of the Worcester Bosch error reappearing.
Helpful Resources
Worcester Bosch Support: https://www.worcester-bosch.co.uk
Gas Safe Register: https://www.gassaferegister.co.uk
UK Boiler Safety Advice: https://www.gov.uk
Frequently Asked Questions
What does the E6 error mean on a Worcester boiler?
It means the domestic hot water temperature sensor is faulty or disconnected, which can affect your heating system and central heating CH flow.
Can I fix the Worcester E6 error myself?
No. A qualified engineer should inspect the sensor short circuit, gas valve, or burner control unit.
Why does the hot water go cold suddenly?
A failing hot water temperature sensor, temperature difference error, or incorrect code plug may cause system confusion.
Can 0800 Homefix repair this on the same day?
Yes. We resolve faults from flow negative thermistor coefficient to code plug not detected in a single visit.
Does E6 affect the heating mode or central heating?
It can, especially if the high limit thermostat or temperature limiter in central system triggers shutoff.