Jaguar Combi Boiler F0 Error

This is a common fault on these boilers that I get called out to regularly. Customers think that there is a serious problem with the boiler and it requires an engineers attention. In reality the problem is usually caused by the pressure being too low in the central heating system.

The boiler contains a water pressure sensor which measures the pressure in the central heating system which will need to be topped up every now and again. How often it requires topping up will depend upon the system but may only be once a year. When cold the water pressure should be topped up to around 1.5 bar. If the water pressure drops to 0.5 bar or below the F0 error will be displayed and will occur if the system is drained or the pressure drops over time.

To top up you need to press the bar button which will show the current pressure in the central heating system. Then on the flexible filling loop which is usually fitted to the pipework below the boiler the cold water inlet valve needs to be opened. On the standard filling loop which came with the boiler you will need a large-headed flat screwdriver or small adjustable spanner to open the valve. On a better quality filling loop it may have a washing machine style tap. Whilst the system is filling you may need to press the bar button again because the display will revert to the system temperature. Once the water pressure is up to 1.5 bar it is important to turn the filling loop fully off, ideally disconnecting the flexible pipe to ensure the system isn't overfilled. If you do put too much water in the system you will need to drain some out to avoid causing further problems.

As soon as the water pressure gets to 0.7 bar the F0 error will be cleared and the pump may start up to help clear any air out of the boiler. If the pressure drops regularly it may be due to a leak and further attention from an engineer may be required.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.

Jaguar Combi Boiler F1 and F3 Error

Another engineer had been to look at a Jaguar Combination boiler that was coming up with the error code F3 and not giving good hot water. He stripped out the plate heat exchanger and cleaned the dirt build up out which seemingly solved the issue.

However, the problem started occurring again and so I booked an appointment to have a look at the problem myself as the other engineer was on holiday. The next day the F3 fault had escalated to an F1 fault and the boiler was failing to light so I attended the same day. I looked at the boiler and it was a sparking but failing to light, but there was no problem with the gas supply. I realised that the F1 code was due to the overheat thermostat cutting the boiler out and not allowing the boiler to light. I reset the overheat thermostat and the boiler was able to light again.

Running the boiler for the hot water, the boiler got up to temperature quickly and cut out before the hot water was hot at the tap. The hot water would then got quite hot and then the boiler would relight as the boiler cooled down. The water would cool before the boiler could catch up. The boiler was also quite noisy suggesting that the circulation was poor. There didn't feel like there was much vibration coming from the pump. I removed the central screw on the pump to check that the spindle was free. When the boiler was running the pump was spinning but it didn't look as fast as it should be.

Fortunately the customer had a replacement pump and housing in his garage. When changing the pump I changed the fibre washer on the top connection as they don't seal very well when reused. I also had to clean the brass spindle that the pump slides onto as there was a fair amount of scale build up on it which was preventing the o-ring from making a good seal.

Replacing the pump solved the F1 and F3 errors and the boiler was running well although the hot water was still quite hot it was modulating well.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.