Engine Temp High reduce speed
 

Been having some engine temp problems with my V70 163BHP 2010. Thermostat and temp sensor have been changed. Live data shows temp of 112deg providing I switch A/C off and drive at 55-60 mph.
Last week I took the car for diagnostic check at non-franchise Volvo and they reported the following.
1) Glow plug relay faulty (Glow plugs working on 2 cylinders) All new fitted 6 months ago
2) Regen unsuccessful
3) Cooling fan control errors.

I spoke to the mechanic and he explained that the glow plugs are used to carry out a regen, in my case this was not being completed and the car was constantly running hot trying.
The cooling fan control unit was not switching the cooling fan as and when required.
This all makes sense, I was aware when starting in cold weather the engine was lumpy.
3 days later and they haven't got back to me with a price.
A few questions:-
Does a new relay need to be coded to the car? If not where is it situated? and can I just replace it?
If I can replace the relay Is it possible to jump the cooling fan control unit? for test purposes to try and force a regen? (100% fan).
Thanks

I would personally want to deal with them one by one to see what the impact is....

So I'd get the glowplugs sorted - this might cure the regen (it is a plausible explanation).

Once that's bottomed - do you still overheat?

The fan running or not I don't think will make any difference at 55-60 mph, the air going through the rad at that speed will be many times greater than then fan could ever manage. That said you don't want to overheat in summer traffic either, but I'd check the operation of the fan once the plugs are sorted. You'd also want it working if you force a regen through VIDA.

Do you know if fitting a new relay requires programming through Vida?

View the live temperature data after opening all vents, climate temperature dials on maximum heat and climate fans on full blast.

If coolant temperature doesn't drop significantly and if the air out of the vents isn't noticeably warm/hot, you've probably got a clogged heater matrix which may be solved with forward and reverse flushing.

I've never done one I'm afraid so can't answer...

The heater controls and selected temp work fine. Even if the matrix was blocked, surely this would just replicate the car temp being selected to low and wouldn't cause the water temp to rise.
Also the confusing thing is that when the car is stationary but engine running, the temp immediately drops a few degrees. No loss of fluid. I even drove the car for 60miles last week at 60mph and no overheating warning came up. As usual when car parked up the cooling fan sounded like a jumbo jet. When live data of cooling fan is monitored it does increase from 23%>97% which indicates the ECU has instructed the Cooling fan control module to ramp up speed.

That's not how your cooling system works.
Definitely read what I said again and if you do that, you'll make a bit of progress then we'll see from there.

Diesel engines produce less heat than petrol engines and it would be quite normal on a cold day if you have the cabin heater on and the car is stationary for a while for the temp gauge to drop below "norm" slightly - especially on the smaller 4-pot FoMoCo engine cars.

Yes I know.
I'm asking the OP to observe temps in different circumstances to see if his car behaves like a normal car.

I was responding to the OP when he said "Also the confusing thing is that when the car is stationary but engine running, the temp immediately drops a few degrees. "