code 54 water in fule filter

[Tedwalking]

I have a problem with my 2012 Astra gtc 1.7 cdti sport 40.000 miles I have owened it for about 6 months now and all is good except that about 6 weeks ago code 54 WATER IN FUEL FILTER came up and then it whent a way but in the last 2 to 3 weeks it comes on at each startup, then after 5 mins it has gone off, So I decided to change the fuel filter the car seems to go a lot better but I still get CODE 54 COME UP each time I start up, can anyone tell me what it could be and what to try next. By the way I did not find any water in fuel filter when I drained it.
Thank You
Ted

[Rusty2009]

It could be a few things best getting it plugged and seeing.

Here's a couple of links I know it's for a 1.3 but pretty much the same.

https://workshop-manuals.com/vauxhall/as...diagnosis/

https://workshop-manuals.com/vauxhall/as..._draining/