Worcester Bosch Greenstar 4000 System fault 238

What it means

Locking fault (V category). Fault relating to the boiler electronics, related to gas valve circuit checks.

Likely causes

1. Low or no gas supply to the property, or restriction on gas valve inlet
2. Loose connection on the gas valve or board
3. Faulty continuity down harness
4. Incorrect voltage to the gas valve
5. Water ingress on the gas valve connections
6. Incorrect gas valve resistance
7. Incorrect gas type
8. Incorrect gas supply pressure
9. Faulty flue system
10. Incorrect gas/air ratio
11. Faulty gas valve
12. Faulty seals around the burner, internal flue seals or case seals causing abnormal O2/CO2 readings
13. Flue system integrity failure
14. Combustion circuit fault

Where to start

1. Check the gas supply to the property and the inlet on the gas valve (check drop on inlet).
2. Check the connections on the gas valve and the board (loose connection).
3. Check the continuity down harness and replace if required.