We were called to diagnose a Scania R420 with a customer complaint that the engine would intermittently turn off whilst driving and would take some time until it would be possible to restart the engine.
As the truck was a daily runner, the client wanted the truck to be diagnosed and repaired as soon as possible, we started off with the basics and confirmed the fault by taking the truck on a road test and confirmed it would intermittently shutdown and take time to restart.
When it did shut down, we queried the EMS (engine management system) for fault codes using our dealer Scania scan tool and to our surprise the EMS would not communicate, this test was repeated when the truck was able to start and communication was restored with no fault codes.
This test concluded the issue was to do with the EMS going offline, to verify whether the issue was to do externally (wiring) of the EMS or internally, wiring and integrity was checked which checked out and pointed to an internal EMS fault. With our experience on Scania EMS systems, this is a common fault and can either be rectified by board level repair or replacing with a brand new or used donor EMS.
Once the EMS arrived through DHL, we programmed it to the truck without the need to replace the wholse set such as the COO and so on, which guaranteed factory coding and not losing any configurations/codings whatsoever.
The truck was sent on a road test and returned with no faults whatsoever, the client was delighted to have his truck up and running without any pointless parts replacements or trial and error work!