Gearbox intermittant fault

[Matthew spencer]

Hi people can any one help me i have a 2003 2.4 petrol and when starting out on a journey it wont select 4th until you have covered a few miles. On a motorway journey the other day it was fine till we pulled off for a leg stretch then when we continued the journey it was in 3rd and would not select 4th until 10 miles or so on the motorway then it just started working again can anyone help with this as i dont want to go to the expense of a new gearbox if its a simple sensor or relay etc

Any advice is much appreciated

Thanks matt 

Forgot to mention its had gear box oil changed but not the filter as garage said it was gearbox out to change the filter which i thought seemed extremely

Edited August 30, 2019 by Matthew spencer
Forgot to mention

[MonsterS]

I always change, clean the filers and magnets. Not hear of this error. Light be worth taking it to a gearbox expert.

[Matthew spencer]

Thanks for your reply when the gear oil was changed it came out like treacle so it hadnt been done in ages some days it has no problems at all im wondering if its just a loose connection on something. Ill get it booked in and looked at

thankyou

[MonsterS]

If it was like treacle then was there any metal shards or shavings in it? Might be the clutch slipping.