We have a Sprinter 311 cdi 2002. It has been stood for 3 months and now we have come to start it again, the pre-glow light is comes on again after the enging has started and stays on. No problem starting and runs fine once started. Is this likely to be the glow plugs or could it just be a relay? The van has done ove 211K but don't know if glow plugs ever been changed. We bought it on app 190K. Any suggestions would be welcome. Thanks.

Jane, April 2009

First, it is either a glow plug or glow plug control module, easiest test is under the battery sits the module, disconnect the white 5 or 4 wire plug, put a test light on the pos of battery and probe each loom terminal. call me if you want further assistance all details are on my web site

williamsdiesels.com, April 2009

its a possibility that the glow plugs have never been changed it could be the glow plug sensor is indicating that one of them is faulty and sending this information back to the relay, It also could be down to a bad i.e bad earth connection take of leads to glow plugs and clean also disconnect battery terminals and leave for a few hours its should reset itself, Note its a possiblity that that the sensor is telling you that one of the plugs is not working, The other way to find out is to remove all glow plugs and turn on ignition and see which ones get hot and which one does not and replace!

Ian Mechanic, April 2009