Worcester Bosch 1065 fault codewhat it means and how to fix it
The system pressure sensor is faulty or not connected. The boiler cannot read its own water pressure, so it stops rather than guess. Worcester check the plug, the harness, the voltage, then the sensor.
Take care
Get a Gas Safe registered engineer to look at your Worcester Bosch 1065
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What 1065 means
The Greenstar 8000 Life and its relatives read heating system pressure electronically rather than from a gauge alone, and 1065 is the code for that reading having gone missing: system pressure sensor faulty or not connected. On the 8000 Life combi and system boilers it is a blocking fault, on the 4000 it is filed as a maintenance code, and the Worcester 2000 words it pressure sensor faulty or not connected. Whatever the category, a boiler that has lost its pressure signal will not run normally, because low pressure protection, the pressure readout on the display and — where fitted — the intelligent filling system all depend on it.
Worcester's remedy is a wiring sequence: check the water pressure sensor plug is connected, plug it in correctly, check the harness for continuity, check the voltage to the sensor and the return voltage from it, and only then replace the sensor. The order matters because the sensor sits low in the boiler where a plug can be knocked during a service or a filling-loop job, and a dislodged plug is far cheaper than a sensor. This is not the same as low pressure. Low pressure is 1017 or 2971 with a working sensor and a real shortage of water; 1065 is the sensor itself.
On the Compact ranges the equivalent is CF 288 or CF 289, water pressure sensor not connected or short circuit to supply or to ground. The CDi Classic and Greenstar i have no pressure sensor and cannot show any of these. The householder can look at the pressure readout — if it shows something impossible, or nothing, that confirms the sensor — but the fix is behind the cover.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Sensor plug disconnected or not seated | Worcester's first two checks. The plug is easily disturbed during work inside the boiler, and a partly seated plug reads as an open circuit. | Common |
| Harness broken or shorted | The third check: continuity down the harness, replace if required. On the Compact the two CF codes distinguish a short to supply from a short to ground. | Occasional |
| Sensor failed | If the plug and harness are sound and the voltage is present but the signal back is wrong, the sensor is replaced. | Occasional |
| Water damage at the sensor | A sensor sits in the wet part of the boiler. A leak from a nearby joint onto its connector produces exactly this fault. | Rare |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£90–£200
Time on site
45 minutes
Reseating the plug is the visit, £90–£140. Replacement pressure sensor £120–£200 fitted.
Typical UK prices including parts and labour, updated September 2026. Your quote may differ.
Parts you may need
We may earn a commission if you buy a part through one of these links. It does not change what you pay, and it does not affect which parts we list.
Worcester Bosch Greenstar control board (PCB)
£250–£450Authorised Worcester parts distributor
Price checked 28 September 2026
Worcester Bosch Greenstar system water pressure sensor
£25–£60Authorised Worcester parts distributor
Price checked 28 September 2026
Own this appliance and had this code? . Nothing is published until a person has read it.
Related Worcester Bosch fault codes
- CE 207Get it checkedSystem water pressure has dropped too low for the boiler to run safely. Topping the system back up to 1.2 bar usually clears it in five minutes.Related: water pressure
- H07Get it checkedA maintenance warning, not a lockout. The boiler is still running but water pressure has fallen far enough to limit how well it heats.Related: water pressure
- 2970Get it checkedThe heating system's pressure has dropped too quickly too often. On an 8000 with the intelligent filling loop this usually follows venting after an automatic fill; otherwise it is a leak that needs finding.Related: water pressure
- EA 227Stop — call an engineerThe boiler tried to light and never detected a flame, so it has shut the gas off and locked out. This is the most common Worcester fault code.Related: same brand
- E9 219Stop — call an engineerThe boiler has overheated and the safety thermostat has tripped. Water is not carrying heat away from the exchanger, and it should not be run until that is fixed.Related: same brand
- C6 224Get it checkedThe fan is not reaching the speed the boiler asked for, so combustion cannot be confirmed as safe and the burner has been prevented from firing.Related: same brand
Own a Worcester Bosch boiler? Save it and its codes come first next time.
Related guides
Common questions about Worcester Bosch 1065
Is 1065 the same as low pressure?
No. Low pressure is 1017 or 2971, and on the 8000 Life the display alternates LoPr with the reading. 1065 means the sensor that would tell the boiler its pressure has stopped answering.
Can I still top up the system?
Physically yes, but the boiler cannot see the result, and its protection against running dry depends on the sensor. Have the sensor fixed first.
Does my Greenstar i have this code?
No. The Greenstar i and CDi Classic use a mechanical gauge and have no pressure sensor code. The Compact ranges publish it as CF 288 and CF 289.
Technical review
Not reviewed by an engineer
No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer technical and service documentation
This page has not been reviewed by an engineer, and we would rather tell you that than imply otherwise. The severity rating follows what the manufacturer publishes: where they say isolate the appliance and call someone, so do we.