Volvo V50 (2010) intermittent 'brake system failure' error code:PLEASE HELP!
 

Dear all,
I would very much appreciate any help and advice with the following issue:
I purchased a second-hand volvo v50 1.6 S drive 3 months ago with 117,000 miles on the clock (full-service history- ex-fleet car). The car was very reliable until yesterday. On a long and hot family trip, I stopped at the service station. When restarting the car, the message 'brake system failure please stop saftely' appeared on the dash board and the car went into limp mode. I turned the car ignition on and off about 3 times, only to receive the same message. I waited a further 3 minutes and then suddenly the error message disappeared and the car started and we drove for about 1 mile on the motorway. After 1 mile passed, the error message appeared again and we safely moved the car onto the hard shoulder of the M6. We called the RAC recovery truck out and the mechanic disconnected the battery and deleted what appeared to be several error codes (see pdf attached)- none related to the brakes though. Somehow we managed to drive 25 miles home without the error message cropping up. Now that the car is parked at home, I am terrified to drive to work without it breaking down. I have contacted several mechanics and garages who have either told me that they do not have the software/ volvo kit to retrieve the deleted error codes, or that I should wait until a new error code appears and then take it to the garage. To save costly trips to garages, I have decided to try and isolate a few of the problems myself, but I have no idea where to start. Has anyone else experienced this issues and could you tell me what you did first please? It might be worth mentioning that three days before this error appeared, a mechanic checked over my air con unit and ran a few diagnostic tests to check for leakages.
I have looked through several related threads and my guess is that It could be a simple as cleaning the CEM and contact modules, or it could be a new ignition or immobilizer problem. I am very frustrated- having purchased a volvo for their apparent reliability. Now it seems that I have made a £3,400 big mistake. PLEASE SEE THE ERROR CODE PDF ATTACHED
Any thoughts/advice would be most welcome.
Many thanks!!

The codes should still be in the computer - typically disconnecting the battery does not erase the stored codes. Even if the warning light goes out the codes should still be there. You will probably need to go to a dealer or a Volvo friendly shop as not all code scanners will read the ABS codes and the Volvo proprietary codes. The codes I see suggest you may have had a battery or alternator issue - ie when the voltage drops below a threshold, the computers can throw all sorts of codes related to communications. Some of these codes could have been set long ago and never cleared so I'd expect a shop to record, clear the codes and see what resets. In terms of the braking system, the most common faults for ABS lights are wheel speed sensors, the ABS controller board (more so in the older models which can develop cracked solder joints - not sure if this is a problem for 2010s), transmission speed sensors (the wheels, transmission computer and ABS are all tied together logically) and then the ABS pump system. The CEM is the central electronics module which has relays etc to feed the various components and can act as a monitoring point. Again CEMs can fail but mostly at a relay level - not as a complete unit. Its possible to have a wiring or connector issue so some people try using electronics cleaners on the contacts then reseating the component. As far as your car goes, the first step is to see the braking specific codes. Also, my expectation is that even a complete ABS failure would not disable the brakes but would diminish the performance in a panic stop - best to talk to Volvo people if you have concers