Marinus van der Leest suggests that the problem with the "Automatic Gear Fault" (Fault P055) lies inside the gear shift actuator. Inside the actuator there is a big teethed segment which is driven by one of the electric motors. The tooth play between the teeth of this segment and the drive shaft is very accurate. When it is hot, because of the heat the segment will expand and the friction gets higher. Then, when there is too less grease and/or the battery has not enough power the actuator sticks. With the later actuators there is more play between the teeth of the toothed segment and the drive shaft.
Some 8 years ago the shift actuator in my car was replaced because of malfunction. After repair I asked the mechanic at the Peugeot shop how long the new part would last. He told me it was a new type with modifications. The only difference I see is the part number. The old one was: 3981 009 001, the new one 3981 000 090
Mike El Seem has done further research: There are 2 new versions: Sachs 3981 000 90 and 3198 1000 92 - the difference is the production date of the car respectively ...090 up to 12/2006 and ...092 after 12/2006. The oem peugeot numbers are : 96 825 635 80 for the 092 and 96 493 944 80 for the 090. According to Sachs webpage the ..090/092 are the newest versions of the part.
Remember that when removing the actuator you will need to put it in service mode with PP2000 or else you will have issues when installing it as the ecu now reads an error on it and prevents the car from starting - see below for more info about using PP2000
this shows the internal operating mechanism
Low mileage and little use is not good for these cars - the Molykote G-Rapid paste used in the gear actuators has a limited shelf life ( see here ) so the grease in an actuator made in 2005 will be well past its sell-by date! Many of these actuators last for many miles, some not so long! Mine seems good at 51,000 miles (January 2015).
Mileage is approximately 14,000. The recommendation from the Peugeot dealer was that as they had no idea what caused the problem the gearbox etc should be replaced at approx £3,000 and if that didn't work the ECU would have to be replaced!!
The garage found a fault code for "gear actuator" and replaced the complete unit without removing the gearbox. They frequently have semi automatics in for repair and it is usually the actuator which is the problem. According to them the Peugeot/Citroen manual gearbox which is used on the 1007 before the actuators are added is virtually bomb proof.
He was charged £573 for the actuator, £240 for labour, £35 for a code read plus VAT = £1017 by Newbury Transmissions - Unit 3, Boundary Road - Newbury - RG14 5RR - tel: 01635 552226
Newbury Transmissions also confirmed that providing the gearbox is in "N" when the ignition is switched off there is no problem with towing these vehicles with all 4 wheels on the ground. The only other advice they gave was never ever buy an automatic Mercedes A Class!
Getting to the actuator includes removing the battery and some air ducts that block passage to the actuator. There are lots of clips that have to be removed using a fork/ y shaped tool.
One actuator bolt can be removed from leaning down from above and using a ring spanner. The other requires the same ring spanner to be used from underneath the car.
The car has to be jacked on front nearside and the wheel and wheel arch trim taken off. This is to provide the space to remove the remaining bolts holding the actuator in place. An extended socket set is needed to turn the bolt, as there is insufficient space for a ring spanner. It is a tight space for the socket set to locate through and required one person from above to help locate the socket onto the bolt head.
Removing the wheel to gain access appears to be far easier than removing a whole load more pieces in the engine compartment
Take off the plastic cover and methodically grease all the moving parts inside the actuator - suggest synthetic grease as petroleum-based greases can attack plastic parts. Reassemble to car.
Initially the Peugeot Planet PP2000 system refused to reconfigure the gear shift actuator despite a new battery. The meter check revealed it was below the magic 12.5v when things start to get turned off by the car to save power.
To make absolutely sure, connect the battery and a charger in parallel and run the Peugeot Planet Replacement Part function again. This takes about 10 minutes with the car learning the actuator movements again from scratch and learning the clutch biting point.
The regreased actuator worked well until car was sold.