Worcester Bosch Boiler A5 Error Code — Meaning & Repair Cost (2026)
Hot water cylinder (tank) NTC temperature sensor defect. Below: the most likely causes, and what the matching repair costs — Estimated national ranges with a metro localizer. Reviewed July 2026.
What A5 means
Hot water cylinder (tank) NTC temperature sensor defect.
Likely causes, most common first
- Failed tank temperature sensor
- Damaged sensor wiring
Base: 2 published national repair-cost guides (retrieved 2026-07) · full source registry on the methodology page · Code meaning & causes · Reviewed July 2026
What it usually costs to fix Estimated
A5 on a Worcester Bosch boiler resolves to the boiler no hot water problem. Worcester Bosch parts typically run ×1.15 against the mainstream baseline (UK domestic-boiler market leader (~26% market share, ~half a million units/year) explicitly described as a premium-positioned brand. A direct UK installed-cost comparison shows Worcester Bosch running £1,500-£2,500 (combi swap) to £2,000-£3,000 (full system) — below sister-premium Vaillant's £2,000-£3,500 range at comparable tiers, but above a mainstream ducted-brand baseline.), and the ranges below already include it.
$315–$1,160 national estimate to fix the fault behind A5 (Worcester Bosch parts ×1.15). Enter a ZIP to localize.
| Most common repair | Typical total | DIY? |
|---|---|---|
| Circulator pump replacement | $315–$1,160 | Pro recommended |
| Domestic hot water (plate/secondary) heat exchanger replacement | $525–$1,075 | Pro recommended |
Plus a typical service-call / diagnostic fee of $75–$150, often credited toward the repair.
Pick a quality tier for a class-typical estimate, or a specific brand to override it (brand adjusts the parts portion only). Enter a ZIP or Canadian postal code to localize to your metro's labor costs. Everything updates without a page reload; no data leaves your browser except the shard lookup.
Base: 1 published national repair-cost guide (retrieved 2026-07) · full source registry on the methodology page · National base range (BLS OEWS May 2025 + BEA RPP 2024) · Reviewed July 2026 · Estimated
Codes are universal — your location changes the repair price, never the code's meaning. See the methodology for the exact localization formula and sources.
Reviewed by a Red Seal–certified appliance technician who also holds a Technical Safety BC gas ticket (Gas-C) and an ODS/halocarbon refrigerant ticket (CFC/HCFC/HFC).