Citroen C5 auto gearbox problem

check the usual things like condition of auto gearbox fluid,make sure it is`nt burnt and check the level is ok,get the fault codes read as well

Take it back to garage that serviced it and them them check it . Oil level should have been checked in the service , so unless any leaks or they missed it , should be o.k.

Limped home as stated (I did not want to stop as was bringing wife back from surgery).

Left it overnight and it's been fine since ... ?

This is a common citroen automatic problem. When this happens it usually means the "car" has detected a fault in the gearbox and the car will lock into 3rd gear, somtimes with a bit of a thump. Even when you stop the car at a road end and try to start off again the gearbox will still be in third gear which can be stressful on the car when starting of again. The best thing to do is to pull over, switch of the engine, then start it up again, the car will now be working in all gears including manual selection. The gear box in this car will be made by a german company called ZF i.e. not by citroen therefore citroen dealerships can somtimes be the worst place to go looking for help. Further to this it must be said that citroen have had a fair share of trouble with this gearbox and are somtimes reluctant to help, telling customers that it is a very rare problem when it isnt. My advise to you would be to take it to an automatic gearbox specialist if the problem returns because this box is delicate compared to others and needs to be dealt with by somebody with experience on the ZF Al4 or 4hp20 gearbox. if you wish to talk about this call me on 07795458216 I have experience with this situation. P.s if you keep your speed at around 50mph the effect of dropping into 3rd gear will not be as severe and remember switch it off then re-start it will continue on its way with out damage. I have had a c5 with this problem for 8 months now and it continues to run just fine on city driving so dont panic. Ask the garage checks they made with the gear box when servicing and get back to me.

Good luck.