How to Fix Worcester Bosch D1-286 Fault Code (UK)
Worcester Bosch showing D1-286 — Return sensor fault. UK diagnosis, likely spare (return NTC 87161066550) and step-by-step reset.
What the code means
D1-286 on a Worcester Bosch indicates return sensor fault. The boiler locks out to protect the heat exchanger and, on gas faults, to comply with the Gas Safety (Installation and Use) Regulations. Always reset to confirm the code is live, not historical.
Likely spare
The most common fix is the return NTC 87161066550. Check the exploded diagram against the GC number on the data plate before ordering — Worcester Bosch revised parts on Worcester Bosch units mid-production.
Fix procedure
Ohm sensor cold ≈10kΩ. Replace if open circuit.
Log the fault and reset. If the code returns within 24 hours, escalate to full electrical diagnosis with a manometer and multimeter.
Frequently asked questions
- Can I reset D1-286 myself?
- You can press the reset button up to 3 times. If D1-286 returns, the boiler needs a Gas Safe engineer — it is illegal to repair gas components without registration.
- Is the part covered under warranty?
- Worcester Bosch standard warranty is 2–10 years depending on model. Registered installations get the full term. Check the sticker inside the case.
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