Error E2 222

Safety precautions:

1. Before doing anything, switch the boiler off at the isolation switch and, if you are going to remove the outer casing or access internal components, switch off the electrical supply at the spur or consumer unit. If you are unsure, do not open the boiler. Do not attempt any work on gas components—only a Gas Safe engineer should handle gas parts.

2. Never repeatedly reset the boiler if the same fault returns. One brief reset to see if the code clears is acceptable but repeated resets risk further damage and may conceal the underlying problem.

Initial homeowner checks you can safely do:

1. Note the exact error code, any additional letters or blink patterns and the boiler model and serial number. This is useful for any engineer.

2. Do a single reset: use the boiler control reset button or turn the boiler off and on. If the code returns immediately or within a short time, stop resetting and proceed to checks below.

3. Visually inspect around the underside/front of the boiler (without removing the casing if you are not competent): look for signs of water leaks, dampness, corrosion or oil on the wiring loom and sensor connectors, and check for obvious chafing or damage to cables leading into the boiler. Also check the condensate pipe/run for leaks that may have dripped onto wiring.

4. Check system pressure on the boiler gauge. Low pressure doesn’t typically cause a shorted sensor but is a general boiler health check; repressurise only following the manufacturer’s procedure if needed.

Specific diagnostic steps (for competent DIYers only):

1. Isolate electrical supply to the boiler at the spur or consumer unit before removing the outer casing. Only proceed if you are confident and safe to do so.

2. Locate the flow temperature sensor wiring. On these Worcester models the flow sensor is usually mounted in the flow pipe or on the heat exchanger with two wires leading to a plug/connector to the PCB. Identify the connector and follow the wiring back as far as you can visually.

3. Inspect the connector: withdraw the connector from the PCB or sensor plug (if accessible) and examine for green corrosion, moisture, bent pins or burn marks. Dry and clean corrosion only if minor and you are competent; otherwise leave and call an engineer.

4. If you have a multimeter and know how to use it safely: with the boiler isolated, disconnect the sensor plug from the PCB (so you measure the sensor alone) and measure resistance across the two sensor wires. A healthy NTC sensor will show a finite resistance in the kiloohm range and its value will change if you warm the sensor slightly (for example by holding it in your hand or using a hairdryer at a safe distance). If you read near 0 ohms (very low single/double digit ohms) that indicates a shorted sensor or shorted wiring. If you read infinite/open circuit that indicates a broken/open sensor or connector. If the resistance is a sensible value and changes with warming, the sensor is likely OK and the fault may be wiring or the PCB.

5. If the sensor is wet or the connector has moisture, dry it thoroughly and leave to dry for several hours, then restore power and try a single reset. If the fault clears and stays clear, monitor the system and get an engineer to check for the cause of water ingress.

If you identify a faulty sensor or damaged wiring:

1. Replacing the flow temperature sensor usually clears E2 faults. Sensor replacement is a straightforward mechanical part swap for an engineer but requires isolation of the boiler and draining of a small amount of system water on some installations. Do not attempt to replace the sensor if you are not confident with sealed system work.

2. If the wiring loom to the sensor is damaged, do not attempt mains electrical repairs yourself. Faulty wiring should be repaired or replaced by a qualified engineer so that correct connectors, routing and insulation are restored.

3. If the sensor measures correctly and wiring appears intact, the control PCB input may be faulty — this requires a professional diagnosis and possible PCB replacement.

When to call a professional:

1. If the fault persists after the visual checks and a single reset, call a Gas Safe registered Worcester‑accredited engineer. Do not attempt gas or PCB work yourself. Provide the engineer with the exact error code (E2 222), the boiler model and serial, and details of what you have checked.

2. If you find fluid or corrosion on the wiring, or if the sensor or wiring tests as short or open, arrange a professional repair. Repeated lockouts, visible damage, or uncertainty about electrical safety all warrant a call to a qualified engineer.

Final notes:

1. If the boiler is under warranty, contact Worcester Bosch or your installer before any component replacement to avoid invalidating warranty terms.

2. Keep a record of fault occurrences and any steps you took — this helps the engineer diagnose intermittent faults quickly. Do not attempt any gas work or mains electrical repairs yourself; a Gas Safe registered engineer should carry out replacements of sensors, wiring repairs, and PCB work.