I have just replaced the main thermostat and EGR thermostat and found it a reasonably staight forward job (bit fiddly getting the T45 Torx screws out of the manifold).
Engine temp never got above 75 degrees before ... now a steady 90 degrees.
THE PROBLEM .... as soon as I drove the car after I'd finished the job the engine 'misfired'. I know it's a diesel and can't misfire but this is the best way to explain the fault, its exactly like a petrol engine where ignition cuts out for a second. It will run ok for a while, then for second or two it will cut out ... then stutters ... then ok ... then stutters. I then got an 'Excess Emissions' error warning on IDrive and engine light (in yellow) is now illuminated on dash. I assume the problems are connected.
It was running perfectly before I did the thermostats so has anyone got an ideas what I could have upset.
For safety reasons I disconnected the battery +ve lead before doing the job ... but I've disconnected it a few times in the past when doing other jobs without any problems, so can't see that this is the cause.
Could I have upset any sensors ( quite a bit of cooling water ran down the front of the engine when I was bleeding the air out of the EGR bleed screw) could this have got in to any electrics?
Any suggestions most welcomed.