Worcester Bosch Greenstar CDi Classic Fault Codes
The Worcester Bosch Greenstar CDi Classic is one of the most widespread premium combis in Britain — the 29CDi, 34CDi and 38CDi Classic sold in huge numbers over more than a decade, and hundreds of thousands remain in service. It is an earlier control generation than the current 4000/8000 platform, and its fault reporting reflects that: codes such as EA, CE 207, C6 and D1 appear on the digital display, in most cases with the sub-code shown alongside or retrievable by an engineer. Age is the CDi Classic's defining diagnostic context. These are well-built boilers, but many are now 10–15 years old, and the faults that arrive are increasingly wear-related — diverter valves, pumps, sensors and heat-exchanger fouling — rather than the installation teething problems of a new boiler. The codes below are the ones CDi owners search for most, each linked to its full cause-and-fix page.
Where Greenstar CDi Classic fault codes appear
The CDi Classic has a digital display on the fascia showing the flow temperature in normal running; on a fault it shows the code, often alternating or paired with a sub-code (for example "CE 207" — low system pressure). Codes beginning E and C dominate. Note exactly what is displayed, including any second number, before resetting.
Resetting a Worcester Bosch Greenstar CDi Classic
Turn the control knob to the reset position or press the reset button (model-year dependent — the fascia is labelled) and hold briefly; the boiler clears and retries. Low-pressure codes want the system topped up to 1–1.5 bar first. On a boiler of this age, a code that keeps returning after reset has almost always earned an engineer visit — wear faults do not reset away.
Common Greenstar CDi Classic problems
On CDi Classics we see pressure-related codes (CE 207 above all — these systems weep pressure as they age), EA ignition lockouts, and the D1/E9 temperature-sensor and overheat family as sensors and pumps tire. Hot water lukewarm or intermittent alongside codes often points at the diverter valve, a known service item on this range. Regular servicing genuinely extends these boilers — much of what kills them is preventable sludge and scale.
Most common Greenstar CDi Classic fault codes
- EA EA on a Worcester Bosch boiler is an ignition lockout: the boiler tried to light its… Read more →
- CE 207 The CE 207 fault code on Worcester Bosch boilers is one of those codes where the… Read more →
- C6 The C6 fault code appears on Worcester Bosch boilers when the control system detects that… Read more →
- D1 The D1 fault code appears when your Worcester Bosch boiler is unhappy with the reading… Read more →
- E9 The E9 fault code means the safety temperature limiter on your central heating flow… Read more →
- A1 The A1 fault code on a Worcester Bosch boiler indicates that the circulation pump is not… Read more →
- F7 The F7 fault code means your Worcester Bosch boiler's ionisation circuit has detected a… Read more →
- B7 The B7 fault code — almost always displayed alongside cause code 257 on Worcester Bosch… Read more →