Some thoughts on Clutches & Actuators by our resident Guru Stu

9 Comments23 December 2016  |  Stu

Affecting: C2 C3 Nemo 207 208 1007 Bipper

Dispelling a few myths about piloted manual gearboxes, or senso-drive transmission of Citroen C2 & C3.

Thinking back a few years, I had heard a few nightmare stories about auto gearboxes fitted to the new small Citroens, firstly it was tales of having to replace the gearbox, along with the clutch actuator and gearbox ecu, and its still got the same problem (the nature of which was never very clear). There were also many cases of the engine being impossible to start, in fact at Euro Car Care we dealt with quite a few cars which had been recovered to us with suspect battery problems, batteries had gone flat and then the car wouldn’t start- we would then do a diag check on the gearbox ecu to find a ‘power latch fault’ indicating some kind of voltage related fault causing the transmission to prohibit engine starting, may be because the transmission has somehow lost its programming. The battery would then be replaced and we would re-initialise the gearbox / clutch actuators and the car would start. We then started seeing a few actual clutch actuator failures, although they were not always attached to the car – they were brought to us by other garages who had replaced clutches or had recovered broken down cars and removed the clutch actuator as a possible reason for the car getting stuck in gear or impossible to engage a gear. We stripped down these actuators and found the mechanical adjuster inside the actuator had broken, these adjusters were repaired where possible and fitted back to the car. I have seen only one clutch actuator which had an electrical fault and this had a burnt out electric motor (which can be separated from the actuator), which we replaced from another failed actuator, and one case of input shaft bearing failure of the gearbox.

   Around 2005 the software in the gearbox ecu was updated and this dealt with some driveability problems but mostly allowed the gearbox to remain in ‘auto’ mode after manually changing gear (the earlier system reverted to manual mode if the ‘flappy-paddles’ were used) This software can be installed in the earlier cars and this update sometimes seemed to cure clutch faults for a while.



 Fast forward to today – how do we approach suspect problems with senso-drive gearboxes? Well, in at least 90% of cases, the symptoms are caused by a worn out clutch. It is quite surprising how the life of the clutch plate can vary so greatly, we find worn out clutches at as little as 30,000 miles and I feel that an average clutch will last between 50,000 and 80,000 miles. Experience has taught us that interrogation of the customer and listening to the description of their symptoms is the best way to diagnose gearbox problems. It has also taught us that there is no temporary or cheap cure.


 If an intermittent fault occurs which appears to be related to the clutch / gearbox, it will not be a one off, the fault will return unless something is replaced, and usually it will be both the clutch and the clutch actuator, unless you want your customer to lose faith in your competence. The actuator may be re-usable but it is impossible to know without re-fitting and testing for some extended time, the labour time for replacing the actuator alone is 2.5 hours which is included in the time for replacing the clutch so it makes sense to replace it while the clutch is replaced. It appears that the clutch actuator self adjusting mechanism will not always continue to work after it has adjusted to a worn clutch then re-set.

   We always do a diagnostic check and record any fault codes and test drive the car before estimating the repair (its never safe to assume anything), you can sometimes get the feel that the clutch is not responding as it should and its worth listening to the transmission for clutch bearing / gearbox noise. The usual recommendation is to replace the clutch kit and clutch actuator and this is the only way to ensure the customer will not return with a subsequent fault and is the only way we can give a warranty on the clutch or actuator.

VERY occasionally the gearchange actuator can fail, I know of one which was faulty due to wear of the engagement motor brushes.


12 April 2018  |  10:21

Hi how are you?i have a faulty citroen c2 gearbox it advisable to buy any gearbox ecu with a different part number online eg ebay?the nearest citroen dealer is in south africa and im in zambia.whats your advice?thanks

13 April 2018  |  11:41

You can swap gearbox ECUs for ones with different part numbers and it wonít do any harm but it might not work or the gear changes or clutch operation might be wrong. I do have a number of ECUs so if you could send your chassis number and the numbers off the ECU I might be able to find something. Are you sure itís the ECU, they donít often go wrong, what are the symptoms?

18 December 2018  |  18:36

Long time well,we have been trying to fix things out but now it's seem we are stuck..I manage to replace the edu gearbox,clutch kit and as well as the clutch actuator.the vehicle can't engage in gears after programming the edu gearbox using the old data from the damaged we want to try and reprogram it direct on the vehicle with all the components are attached as our last option but we need 14 volts to do that.what's your best advise?

Richard Cooke
21 November 2018  |  15:37

I've a c4 grand picasso that has problems selecting any gear when first started, fault code P1755. Sometimes after the engine has been running for 30 mins it will start working, but not always. I'm being told it could be either the actuator ecu or that it could just need a new clutch and slave. Any advice would be greatly welcomed.

18 December 2018  |  18:41

Long time well,we have been trying to fix things out but now it's seem we are stuck..I manage to replace the edu gearbox,clutch kit and as well as the clutch actuator.the vehicle can't engage in gears after programming the edu gearbox using the old data from the damaged we want to try and reprogram it direct on the vehicle with all the components are attached as our last option but we need 14 volts to do that.what's your best advise?

John Haskell
28 October 2020  |  2:17

well explained you deserve to be mentioned by Citroen.
Out of curiosity what is t in the clutch actuator that fails is it a mechanical component or an electrical item
John Haskell

Peter Mathonsi
22 February 2022  |  6:56

I have got a c3 that was having a faulty clutch actuator we bought a second hand and get it installed and the car only drove for a week and it stuck again and mechanic advise me to buy a brand new one which I did on eBay now the new actuator has arrived and do you have any idea if the car will drive for how many months before it stuck again? Or to replace the clutch Actuator is the best solution for the problem or what is causing it to break ?

04 April 2023  |  20:59

The operation of the clutch actuator is describeded in the diabox / lexia clones software. Its very interesting and I dont think was made public when the system was launced in 2002 and most of the descriptoons were written. The first version of the software didn't work hence all the awful reviews. This was corrected around the time the C3R was launced. This car has several refinements like a new gear selector and speed sensing Power steering. The car is entirly drive by wire in practice. It is terrible susseptable to battery issues. It needs two top quality AGM batteries at least. I use a Yuasa YBX9027 AGM stop/start and have upgraded the F4-12B ,under passenger seat, gearbox battery to a lithum version. The clutch actuator is interesting. It has a rachet mechenism in the base that allows for clutch wear. Its oftern worth while changing the entire unit,as pricese are resonable, but you can carefully diasemble it ,reset and re lube it. More of an issue are the counters. These record the clutch usage in an attempt to calculate the clutch thicknes and hence how long you can slip it before it over heats. These need resting after a clutch change. Then there's the mechcanical positioning of the actuator and the clyutch actuating arm. The regular resetting of the clutch bit point by 10 forward and reverse operations on the flat solves the bite point problem.
The Gearbox actuator needs regular silicon grease spraying .
The Stop Start alternator is the pride and joy of the system. Enormous power outut. Needs a good drive belt. Needs no bad connections. Needs replacing about every 60,000 miles when it fails. Its job is to stop the engine at about 10 degrees before TDC. When the engine restarts just the cylinder thats about to fire gets a little extra fuel and the engine starts silently, Years ahead of current start stop engines. It is also used to put an extra load on the engine to help with a quick warm up and charge the battery when de-accelelerating before it applies the brakes. 21 things have to be correct before the stop start can begin.