Andrews E19 Fault Code: Causes, Fixes & Repair Costs
What does the Andrews E19 fault code mean?
The E19 fault code on Andrews CWH-series water heaters signals that the system has detected water pressure below the minimum operating threshold — typically under 0.5 bar — which causes the unit to shut down as a protective measure. In some cases the code can also point to a fault with the pressure sensor itself or, less commonly, an internal Master Board control error. The unit will not produce hot water while this fault is active. Because Andrews appliances are primarily commercial or industrial hot water heaters rather than standard domestic combi boilers, the E19 can appear across several CWH-series models, and the exact trigger may differ slightly between product variants — always cross-reference your specific model's documentation.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- System pressure too low Common
The most frequent trigger. If the water pressure in the system has fallen below approximately 0.5 bar, the appliance locks out to protect internal components. This can happen gradually through normal system operation, or more suddenly if there is a leak somewhere in the pipework, radiators, or the appliance itself.
- Faulty or contaminated pressure sensor Sometimes
The pressure sensor (also called a pressure transducer) can give a false low-pressure reading if it becomes dirty, corroded, or develops an internal fault. Inlet filters that are partially blocked can also restrict flow and cause the sensor to read incorrectly, even when mains pressure is adequate.
- System leak causing pressure loss Sometimes
If topping the system up temporarily clears the fault but it quickly returns, water is escaping somewhere — a leaking radiator valve, a weeping pipe joint, or a failing pressure relief valve. A persistent leak needs to be identified and repaired before the pressure issue can be properly resolved.
- Pump failure or circulation blockage Sometimes
A seized or under-performing circulation pump, or a build-up of sludge and debris in the pipework, can reduce water flow to the point where the pressure sensor registers a fault. Airlocks can cause similar symptoms.
- Wiring or connection fault to the pressure sensor Sometimes
Loose terminals, corroded connector pins, or damaged wiring between the pressure sensor and the control board can cause intermittent or persistent E19 faults, even when actual system pressure is perfectly normal.
- Master Board (PCB) internal fault Rare
The Andrews CWH documentation lists E19 within a sequence of Master Board blocking codes covering control and measurement errors. If all other causes have been ruled out, the control board itself may be generating a spurious fault signal due to an internal processing error.
How to fix it
- Check the pressure gauge reading DIY safe
Locate the pressure gauge on the Andrews unit. A reading below 0.5 bar confirms the low-pressure trigger. The normal operating range for most Andrews CWH appliances is around 1.0–1.5 bar when cold — check your specific model's documentation for the exact target.
- Confirm the mains water supply valve is fully open DIY safe
Trace the cold water inlet to the appliance and make sure the isolation valve is fully open. A partially closed valve is a simple oversight that can cause a low-pressure lockout.
- Top up system pressure via the filling loop if below the normal range DIY safe
If pressure is low, use the filling loop (follow the Andrews model-specific instructions in your manual) to slowly bring pressure up to the recommended level — typically around 1.2–1.5 bar. Do not overfill. Once done, close the filling loop fully before proceeding.
- Reset the appliance and observe DIY safe
Once pressure is restored to the correct level, reset the unit using the reset button or by cycling the power off and on. Wait a few minutes and watch whether the fault clears and stays clear. If it returns within a short time, suspect an ongoing leak or a sensor issue rather than a one-off pressure drop.
- Check for visible leaks around the system DIY safe
Inspect radiators, pipe joints, and the appliance itself for signs of dripping water, damp patches, or white lime-scale residue around joints (a tell-tale sign of a slow weep). If you find a leak, do not simply keep topping up — arrange a repair.
- Inspect the pressure sensor wiring for loose or corroded connections Gas Safe engineer
A Gas Safe or qualified commercial heating engineer should check the wiring loom and connector terminals at the pressure sensor. Loose or corroded connections can produce false readings and need to be cleaned, re-seated, or replaced.
- Test and inspect the pressure sensor and inlet filters Gas Safe engineer
An engineer can check whether the pressure sensor is reading accurately and clean or replace it if faulty. Inlet filters should also be removed and inspected for blockage at this stage.
- Assess the circulation pump and pipework for blockages or airlocks Gas Safe engineer
If pressure appears correct but the fault persists, an engineer should verify that the pump is operating properly and that there are no sludge deposits or airlocks reducing flow through the system.
- Call a Gas Safe registered engineer if the fault has not cleared Gas Safe engineer
If the E19 fault persists after restoring pressure and attempting a reset, or if it returns repeatedly, you need a Gas Safe registered (or suitably qualified commercial heating) engineer to carry out a full diagnostic. This covers sensor replacement, wiring checks, pump assessment, leak detection, and — if all else fails — evaluation of the Master Board.
Parts you may need
- Water pressure sensor / pressure transducer · from £25
- Pressure relief valve · from £35
- Expansion vessel · from £55
- Circulation pump · from £85
- Master Board / PCB · from £220
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £90–£380, depending on the underlying cause.
Frequently asked questions
Can I fix the Andrews E19 fault myself by topping up the pressure?
Yes — if the root cause genuinely is a one-off pressure drop (for example, after a recent system bleed), topping up the pressure to the recommended level and resetting the unit is a perfectly safe DIY action. However, if the pressure drops again quickly after topping up, something is leaking and you should not keep refilling the system — call an engineer to find and fix the source of the leak.
How much does it typically cost to repair an Andrews E19 fault in the UK?
For most people, the bill lands somewhere between £90 and £380. A straightforward diagnosis visit plus pressure sensor replacement or a minor wiring repair tends to fall at the lower end. Pump replacement or more involved work pushes towards the top of that range. More expensive components such as the Master Board (PCB) can cost £180–£400 for the part alone, so if that is identified as the cause expect the total to exceed the typical range — at that point it is worth getting a replacement quote for comparison.
Why does my Andrews unit keep losing pressure and triggering E19 repeatedly?
Recurring pressure loss almost always means water is escaping from the system somewhere. Common culprits include weeping radiator valves, a leaking pressure relief valve (which discharges outside or into a drain), a failing expansion vessel, or a joint that has started to seep. Each time you top up without fixing the underlying leak you are simply masking the problem. An engineer can pressure-test the system to pinpoint where water is escaping.
Does E19 on Andrews boilers always mean the same thing across different models?
Not necessarily. Andrews produce a range of commercial and industrial water heaters, and fault code definitions can vary between product series. On the CWH-series, E19 is documented as a low water pressure or pressure sensor fault linked to the Master Board blocking codes. On other Andrews models or older units, the code numbering may differ slightly. Always cross-reference with the manual supplied with your specific appliance, or contact Andrews technical support directly if you are unsure.