No Simon, i would say you have a problem with the Coolant sensor the one that controls the glow plug time to open or close .relays very rarely to malfunction but still a possibility.
To know would be better and easier to have a scan tool hooked up and the system checked for codes ,this will tell you what has to be done to rectify this issue.
One way to test with out the scan tool . is to disconnect the coolant sensor , this is a two pin sensor at the front of the cylinder head .under the front part of the intercooler ,you will have to remove the intercooler to remove the sensor .which looks like this one .
one connection is for the temp gauge and the other is for the glow plug system.
Replace this part is not an expensive item , But i do insist you use a Mitsubishi part
as after markets DO NOT work I've tried them all.
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