ACE Trouble Codes a lesson to remember

2002 Discovery td5 sagging a the n/s/r corner overnight, so I checked the little brass nuts on the valve block one had a slight leak if I moved it, cured that, still doing it so I jumped straight in and changed the air bag on that corner, still doing it, changed the other air bag, still doing it, tried the ride height sensor, still doing it, looked for leaks in the pipes, nothing, then I thought the only thing left is the compressor (wrong!!), so opened the box again, saw the valve block, took it out this time and gave it a squirt of soapy water, there was the leak. Luckily I had a spare here so changed it and had a look this morning - all good . I must remember to check everything before I go changing things

Merry Christmas