Citroen C5 automatic gear fault

Because you say the fault is sometimes cleared by switching the ignition off and back on, I would suspect an electrical connection problem. Check the integrity of the wiring harness to the gearbox, particularly where it enters the the black junction box on top of the gearbox next to the shift cable.

it turns out it was the clutch that was causing all the trouble...got that fixed and everything works fine now...thank you for your help

Have you had a look at this similar problem: Automatic Gear Fault

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Mark.
Your problem has all the trade mark symptons of a citroen automatic box. I cant help thinking that the vibration when starting is not connected to the gear box problem, but what I would say is that 1. your Citroen dealer should have been able to give some clue as to the gearbox fault through diagnostics 2.They probably didnt because they dont believe they can fix it. 3 stay away from Citroen dealerships with this problem and look for an automatic gear box specialist. The gear box is not made by citroen but by a GERMAN company called ZF, therefore most Citroen dealers know nothing about the workings of the gearbox. 4.This will cost money to fix and depending on the cars history may not be fixable.

I will give you some idea on how to go forward with this.
1.Check the gear box model, it will be AL4 OR 4HP20.
2.AL4 boxes have a very specific method of checking the oil level, but it is not difficult and should take no more than 1 hour of time for a mechanic to do, this includes driving the car to raise the oil temp to 60 degrees.There is plenty of info on this on the internet, and a proper autobox garage will know how to do it.The 4HP20 IS EASIER BECAUSE IT HAS AN EXTERNAL OIL GAUGE.
3.If your car has been dealt with by somebody that does not know these types of gear box it is very possible that the car has been over filled with oil and possibly the wrong type of oil.
4.Once you get the oil level corrected/checked you will see if the oil is a red colour. IF IT IS IT IS WRONG YOU WILL NEED TO GET THE CORRECT OIL AND START DILUTING THE WRONG OIL OUT OF THE BOX, THIS CAN TAKE SOME TIME AND NO MATTER WHAT ANYONE TELLS YOU, GET THE PROPER MOBIL ATF LT 71141 OIL TO REPLACE THE RED FLUID.
5.SOME PEOPLE SAY THAT IF THE OIL IS A BROWN COLOUR AND SMELLS BAD IT IS BURNED OUT. HOWEVER I CAN TELL YOU THAT THE CORRECT MOBIL OIL IS A GOLDEN BROWN COLOUR AND SMELLS BAD BEFORE YOU PUT IT IN, SO DONT GIVE THIS ADVISE TO MUCH CREADANCE.
6.You will only be able to drain about 2 litres of oil from the gear box at a time. You will then replace the drained oil with the exact same amount of new mobil oil. Drive the car, repeat the process 4,5,6 times to dilute the poor oil into good oil. This oil is expensive, but can be bought on the internet from many different places, you do not have to buy it from a Citroen dealer.
7.When you know the oil is good and at the correct level drive the car for a day or two to notice any different behavior. If the car behaves better but the fault still comes back, you need to go a step further.
8.There are two valves at the top of the gear box that give trouble. these can be replaced with an updated version made by a company called Borg Warner. It would be best if this was done and a software upgrade to suit the new valves was installed (unfortunately the soft ware upgrade has to be done by Citroen)
9.Before you go buying new valves, get the valve block removed from the box and check that the valve have not already been replaced. You will know the Borg Warner valves because the electrical connector will be black and BW will be stamped on the body of the valve.
10 Changing these valves is not a very difficult job. A compident trustworthy mechanic should be able to do it because you do not enter into the inners of the box but only the outer housing which is an almost oil free area. With all the tools and 2 pairs of hands these valves could be changed in 3 hours no problem.
11.If you are going to have a go at this it would be prudent to remove and clean all the sequencing valves in the valve block at the same time and even open the valve block and clean the matrix aswell. If you discover the 2 top valves have already been changed to Borg Warner it would do no harm to clean these also. Use electrical contact cleaner to do this and opperate the valves with an auxillary 9volt battery as you spray the cleaner into all the open ports. Make sure the cleaner is the type that does not react with rubber or plastic seals.You cannot opperate the sequencing valves with a battery, just remove them one at a time clean well with spray and refit.Some would say you should change the seals every time you remove the valves but I would check the seals visually and if you see no obvious damage/tears then just pop them back in and tighten.
12.These steps are proposed to prevent you from spending money unesasarilly. However the proper oil will cost you about £10+ per litre and you should allow for 12 litres if required(I would do it anyway) If you need valves they will cost you about £80 each and there are 2 of them. Refreshing the oil, changing the valves, and cleaning should require no more than 10 man hours with a good mechanic. This is not a very difficult job, a bit fiddly but not difficult and no speicial tools are needed, just a level head.

If you want to you can call me on 07795458216 and I will be happy to chat.

It is important to remember however that this may not cure the problem but this is deffinately the way to go to in elliminating all the fundamental problems.

The thud you hear when the car goes into limp mode is simply the gearbox locking into 3rd gear, so it is best if you are driving the car to keep your speed in the 3rd gear speed band 50mph max to prevent high rev lock up.(this is normal behaviour and is meant to protect the box)

I might be wrong but I think the vibrating when started from cold may just be because you have a diesel engine and if it does not heat properlly before it starts you will experience some shaking because the engine is not fireing clean on its cylinders, once you pull the car into D it will labour the engine thus not allowing it to move freely as the energy is then being transfered to the torque converter. Get the engine mounts checked. I dont think it is connected to the gear box problem.

Hope this helps.

Hello Mark.
I'm living in Australia and have a 2001 c5. I have similar problems but not as bad. It seems like a clutch is slipping in 2nd gear. I'm not used to automatics but that's what it feels like. I also get a thumping sometimes, growling others. What did they do to the clutch? People here don't know european cars and try to tell me its a sealed unit and only solution is reconditioned gearbox at $4,500 plus labour. Car is worth less. A polish guy working with me said it's likely the torque convertor. I think this is like a clutch in an automatic, is that what they did? Hopefully you can help.
Rob

Tony Fleming made a good job. I have had gear fault five years in my c5 hdi 2003. I had oils changed, and the problem begun. One Guy noticed the oil level was too high, and the problem attenuated but is continuing. I have noticed to be important to wait for five to 10 sec after inserting my key before starting the engine. Some times I have to repeat the sequence. There are no problems (no gear fault) when driving, now 150000 km.. I suppose there is an electric reversible fault somewhere. Some other fault signals disappeared when I checked the fuse boxes and found a little bit corrosion in some fuses. Anyway, I Don't trust the Citroen Service and the automatic fault signals , not the software in the fault checks either(the fault numbers change without any cause relationship)

Tony Fleming made a good job. I have had gear fault five years in my c5 hdi 2003. I had oils changed, and the problem begun. One Guy noticed the oil level was too high, and the problem attenuated but is continuing. I have noticed to be important to wait for five to 10 sec after inserting my key before starting the engine. Some times I have to repeat the sequence. There are no problems (no gear fault) when driving, now 150000 km.. I suppose there is an electric reversible fault somewhere. Some other fault signals disappeared when I checked the fuse boxes and found a little bit corrosion in some fuses. Anyway, I Don't trust the Citroen Service and the automatic fault signals , not the software in the fault checks either(the fault numbers change without any cause relationship)