I have a Passat B7,2.0 TDI,with engine code CFFB,the car takes long time to reach operational temp. ,but it reach (90) but temp. goes down when I drive down a hill or drive on highway,and goes up again when in city drive of traffic jam,so the main suspect is the 4/2 thermostat,I looked at the workshop manual on how to replace it,but it's very complicated and need lots of parts to be taken off so that you reach the thermostat,so it's a nightmare
,and I also replaced the in line thermostat for DSG first,but that didn't help.So my question is has anyone did this job as a DIY,not following the book of course,or it's a job for dealer or certified mechanic only?? please if anyone has done it before,please let me know,Thank you.
Cheers,
Tim