Worcester Bosch E9 Fault Code (Greenstar FS CDi ErP Regular)

Safety disclaimer

Fault code summary

Manufacturer

Worcester Bosch

Fault code

E9

Fault type

Central heating, Overheating, Safety lockout

Severity

high

Reset

Not specified

Applicable models

Greenstar FS 30CDi ErP Regular, Greenstar FS 42CDi ErP Regular

Quick answer

Safety temperature limiter in the CH flow has tripped.

What does this fault code mean?

Safety temperature limiter in the CH flow has tripped.

Common causes

• Safety temperature limiter in the CH flow has tripped.

Symptoms

• The boiler may stop operating.

What can the homeowner safely check?

This information was not provided in the verified manufacturer source.

Boiler reset information

Reset information was not provided in the verified manufacturer source. Do not repeatedly reset an unresolved fault.

When should I call an engineer?

Contact a suitably qualified heating engineer when the fault persists, the boiler locks out, or the manufacturer instructions do not resolve it. For gas appliance work in the UK, use a Gas Safe registered engineer.

Engineer diagnosis

• Investigate the safety limiter trip and the CH flow circuit.

Applicable boiler models

• Greenstar FS 30CDi ErP Regular
• Greenstar FS 42CDi ErP Regular

Related fault codes

• A7 — Greenstar FS CDi ErP Regular

  Hot water NTC sensor defective.

  Read fault code
• A8 — Greenstar FS CDi ErP Regular

  Break in communication to the weather compensating clip-in control or Greenstar Comfort II RF.

  Read fault code
• b1 — Greenstar FS CDi ErP Regular

  Code plug not detected.

  Read fault code
• C6 — Greenstar FS CDi ErP Regular

  Fan speed too low.

  Read fault code
• d5 — Greenstar FS CDi ErP Regular

  Condensate pump fault.

  Read fault code
• E2 — Greenstar FS CDi ErP Regular

  CH flow NTC sensor defective.

  Read fault code
• EA — Greenstar FS CDi ErP Regular

  Flame not detected.

  Read fault code
• F0 — Greenstar FS CDi ErP Regular

  Internal error.

  Read fault code

Manufacturer documentation

E9 | Safety temp. limiter in CH flow has tripped.

Last verified

2026-09-12

Frequently asked questions