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Any idea what could be the cause of these codes. One came on Monday morning an one this morning cleared them an they stayed off for now. The temperature has dropped this week and wondered if it could be this an the fact the cars been stood afew days.

Gearbox was serviced and loom changed 12k ago.

Could be:

Corroded contacts in the plug to the gearbox
Corroded contacts in the plug to the TCU (suggests water ingress - check under carpet insulation for damp)
Failing TCU
Bad harness inside gearbox

Could even be the thing to which the fault code refers, the N215 solenoid valve.

Got under the car tonight. Looks like the plug to the gearbox was loose the locking clip wasn't fastened fully so I pushed the plug in and tightened the clip. So I am hoping this is the cause as I really can not be arsed with a massive issue at christmas time

Could well be. Fingers crossed.

This has started playing up again but intermittently if I start the car up and it flashes up gearbox malfunction I find running through the gears turning engine off and again sometimes works. I checked the plug again and thats tight and I am going to service the gearbox as I did 10k ago with anew filter and harness which I may replace again if it looks bad. Would it be worth replacing the faulty solenoids while sumps off as a precaution.

I also want to check the TCU is it located under the (UK) NSF carpet and is it easy enough to get at.

Same fault code?

18243 and 18228 are both coming up together each time the intermittent gearbox fault flashes up.

I suspect a contact problem rather than a problem with the solenoid valves. I guess it depends how expensive they are. My feeling is that the harness will resolve the problem, but if you've had corrosion on the pins then that might never make a good connection. Have a good look when you replace the harness.

Is the TCU under the drivers carpet I am just wondering if my wet carpet could be causing the issue.

It’s under the passenger side IIRC but if it’s wet on one side it’ll almost certainly be damp in the other.

Cheers for that will get under there and see what it looks like.

From your experince if I am getting the same solenoids coming as a fault could it be the tcu thats at fault.

Could be solenoids or the wiring or the TCU. Not very likely that it's the TCU but it's not impossible.

I lifted the passenger side carpet but all that was there was the something called the comfort module 4bo962258n also carpets bone dry.

Could the tcu be under the drivers carpet ? This may tie in with the water ingress I have on thst side which I think is either the bonnet cable grommet or maybe the ECU plastic box where it bolts to the scuttle.

OK, then it's the other side. The TCU is the opposite side to the comfort module (which does your central locking).

If there's water ingress, then you want to get the TCU out of there before permanent damage is done. They're not cheap (or easy to find).