Tue Dec 06 2011, 12:54pm. Member No: #1. Joined: Aug 07 2006. Location: Northumberland. P1621 Engine ECU : internal fault. P1394 Gearbox ECU fault : Cruise control / speed limiter off request (from the gearbox) I would have thought it fairly obvious the dealer would know where to look from that. I have the same situation in a Citroen C4 2006 gearbox manually driven (etc6) difference is that to me appears Service (gearbox faulty) over 133 km / h in stage 6, also disappears automatically when lower speed under 125 km / h. My car is a C4 Grand Picasso 1.6 HDI EGS, 2007 with 130000 miles. Few days ago, message 'Gearbox Faulty' came up while driving, gearbox when into neutral by itself and I cannot select gears, engine running fine. Switch engine off and restart, manage to engage gears again, got home after this happened 4/5 times in 2 miles ( sorry to the people I have C4 Grand Picasso 2012 1.6 Auto. This morning my dash displayed "Gearbox Fault: Repair Needed". The symptoms following this message was that when i move the selector to Auto it doesn't auto change the gears. I can select Manual and change but it doesnt shift past 3rd gear. Reverse and Neutral are ok. My C4 Picasso has a problem like described by Sturobs but in my case it just happens when I'm driving in road with some holes or if I drive through a speed hill. In that situation, I got the hand brake fault error, ESP fault, ABS fault and automatic gearbox fault. Used Citroen C4 Gearboxes. We are one of the UK’s leading suppliers of quality, low cost used Citroen C4 gearboxes. Our stocks for sale include 20CQ15, 20DM69, 20DM75, 20DP24, 20DP26, 20DP42, 20DP45, 20DP65, 20MB01 and 20MB16 gearboxes. Every C4 gearbox we sell comes tested and warranted. Find the C4 gearbox you need in our store and save up On the gearbox, there is a drain plug in the bottom somewhere and a fill plug on the side. You drain, clean the drain plug, replace the copper washer and put the drain plug back in. Fill the gearbox with oil until the oil starts to weep out of the filling hole. Replace the fill plug. Please include 'year make model' in all questions in this The vehicle is a Wicked Red Grand Picasso, with the new style Managua standard alloys. Haven't had any time to give it a proper detail, so it is looking extremely grubby right now! We went for the 1.6HDi, which comes as standard with the EGS gearbox in Exclusive trim. Fur26o.