BMW 525d E60 LCI - Low Running Temperature leading to DPF issues - R0Scoe

I have a low mileage 37K, 07 which runs at a very low engine temperature, never above the 75 deg required for DPF regen.

I have had the garage replace the thermostat and they say the EGR thermostat is fine. However, the garage run the engine with the car stationary and it gets to the 88-92 deg, however, once on the road/motorway high revs/low revs the car still stubbornly runs at a low temperature even after an hour.

I am worried this will cause DPF and other issues. How can I get the car to operate near design tempertaures.

BMW 525d E60 LCI - Low Running Temperature leading to DPF issues - R0Scoe

Since we have a very hot day (over 20oC) I did another test and managed to get to 80oC after 30 minutes driving, first time ever this year anyway.

Any ideas or should I try to add some cardboard to prevent over-cooling in our non-summer months. Sounds a bit bonkers in this day of super-complex cars.

I'm not so sure if this has always been the case as the car does not have a temperature gauge, you have to resort to a painful way to get the temp shown on the display or using a bluetooth/ODBC interface/

BMW 525d E60 LCI - Low Running Temperature leading to DPF issues - unthrottled

At the risk of sounding insulting, are you sure that you are reading coolant temperature and not oil temperature?! Oil takes a long time to warm up and is more sensitive to ambient temperature than coolant.

BMW 525d E60 LCI - Low Running Temperature leading to DPF issues - craig-pd130

Also, are you getting a fault code from the DPF, saying 'DPF full' or similar?

I've seen from manufacturers' bulletins that coolant temp is one of several parameters involved in deciding when a regen will happen.

But also, pretty much every manufacturer that uses a coated DPF has a mileage-based trigger built into the ECU which will start an active regeneration as a 'failsafe', irrespective of the soot loading in the DPF matrix. This is usually every 800 - 1000km (it was every 800km on my Mondeo, it seems to be around 1000km on my current Volvo).

In my 2 DPF-equipped cars, this mileage-based active regeneration happens irrespective of coolant temp or load. It seems the car hits the specified elapsed mileage, and the ECU hits the 'regenerate' button ... for example, I've noticed regens starting literally one mile after a start from stone cold.

BMW 525d E60 LCI - Low Running Temperature leading to DPF issues - R0Scoe

1. the value checked is Engine Coolant Temperature
It is not engine oil temperature, I doubled checked and can't see a way to read the oil temperature via ODBII.

2. Yes, I had a DPF message pinging every day after 10 mins driving.

According to other forums the BMW require the following to DPF regen
>10Litres fuel
Coolant Temp > 75oC
? Exhaust temp
All needed before regen

I guess I'll need to get a hold of better diagnostics to see details from the engine when last regen triggered etc etc

However, putting all the DPF stuff aside I would really like to solve the low temperature running issue first before dealing with the DPF.

BMW 525d E60 LCI - Low Running Temperature leading to DPF issues - craig-pd130

As you posted earlier, I'd try using some cardboard to block most of the grille -- try and leave a free airflow path to the intercooler, though. I don't know if this is situated in front of the radiator or separately on your car.

BMW 525d E60 LCI - Low Running Temperature leading to DPF issues - dieselnut

" I have had the garage replace the thermostat and they say the EGR thermostat is fine "

This engine has at least 2 thermostats, 1 for EGR & 1 for the main engine cooling, there may also be an oil cooler thermostat but I don't know about this engine. If any of these are slightly sticking open or opening early you will get cool running.

Run the engine from cold for a couple of miles & see which cooling hoses are getting hot & this should lead you to the faulty stat.

BMW 525d E60 LCI - Low Running Temperature leading to DPF issues - raysheppard

could it be a faulty temp sender unit .

BMW 525d E60 LCI - Low Running Temperature leading to DPF issues - R0Scoe

I don't think it is the temperature sender.

If the car is stationary then the temp gets to target.
If running then the passing thermostat shows reduced temp

I doubt the sensor in the cooling could be fouled by some insulating gunk.

I'd be surprised if the tx sensor was say 20oC out of calibration but you never know.

 

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