Engine fan running speed 19% engine wont warm up. is that normal?

[TALLANDREW]

Hi I am trying to diagnose a very slow warmup in my van. 2019 T6 199ps CXEC motor.

basically van doesn't get over 55 degrees in the coolant after 20minuet drive on the motorway.

Using VCDS All the temp sensors are reading sensible numbers but I noticed that the Fan is always on 19% Is that normal?

I tried to turn it off using VCDS but that aborts for safety reasons when I put my foot on the gas to warm the engine up.

when driving the fan is chugging away at 30%

the outside temp is sub zero.

I am convinced that my fan CPU is broken but am reluctant plunge in and buy a new fan because they are so dam expensive.

I have no errors in the car, other people with fan problems reported error codes before replacement.

I was thinking it could also be the 2/3 way valve which sends collant to the Gearbox oil cooler, there's an article on Hella's site that describes this causing the engine not to warm up. I was thinking of putting a clamp on the output pipe to take that out the problem.

VW T6 - engine does not reach operating temperature | HELLA

"

Failure to reach operating temperature caused by defective directional control valve or way valve in the coolant circuit​

With the above-mentioned vehicle model, the engine temperature display may stop at approx. 70 °C. No errors are stored in the engine control unit.

"



Would be great to know what the fan should be doing.

 

[TALLANDREW]

Saturday,03,January,2026,11:11:49:46589
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 11 x64
VCDS Version: 25.3.2.0 (x64) HEX-V2 CB: 0.4671.5
Data version: 20250822 DS365.0
www.Ross-Tech.com


Mileage: Repair Order: 002


Address 01: Engine (04L 906 056 LS)

11:11:41
IDE00025 Coolant temperature 56 °C
IDE00196 Engine oil temperature 66.9 °C
IDE00556 Outside temperature -2 °C
IDE07706 Outside temperature sensor 1: B1: raw value 24.0 °C
IDE07725 Coolant temperature sensor 1: B1: on cylinder head: raw value 55.7 °C
IDE07727 Coolant temperature sensor 1: B1: on radiator output: raw value 34.0 °C
IDE07832 Coolant fan 1: activation 19.00 %
ENG105980 Duration of the FAN dutycycle gap 0 s

 

[mmi]

I noticed that the Fan is always on 19% Is that normal?

Does the fan actually run then? What I have seen on other T6 engines, they report 10% when the fan is not running.

IDE00556 Outside temperature -2 °C
IDE07706 Outside temperature sensor 1: B1: raw value 24.0 °C

?

Could you please post a couple of VCDS blockmap files

COLD ENGINE OFF
1) Engine (01) blockmap - Ignition ON/engine OFF
2) DSG (02) blockmap - Ignition ON/Engine OFF
3) Aux.heater (18) blockmap - Ignition ON/Engine OFF

COLD ENGINE IDLING
4) Engine (01) blockmap - Engine idling (please turn off Stop/Start)
5) DSG (02) blockmap - Engine idling
6) Aux.heater (18) blockmap - Engine idling

HOT ENGINE IDLING (after a 15+ minute drive)
7) Engine (01) blockmap - Engine idling
8) DSG (02) blockmap - Engine idling
9) Aux.heater (18) blockmap - Engine idling


How-to create a blockmap file:

[VCDS]
[Applications]
[Controller Channel Map]
- Single Controller Address = 01 for engine, 02 for DSG, 18 for Webasto aux.heater
- Login or security access code: Leave blank
- Function: Measuring values
- Output: CSV file
[Go]

The result CSV files are saved into dircetory C:\Ross-Tech\VCDS\Logs

 

[TALLANDREW]

Thanks for the reply

At 19% the fan is physically running. As you said if you turn it off with vcds it stops but says 10% in the measurable values.

So the car was sat cold in Garage I did the 2 sets of cold readings.
I drove first for Diesel when I pulled up Aux heater was running.
I then drove a 15-20minuet cross country loop to the super market, when I pulled up the heater was off. I did the Hot readings.
Then I drove home, the auxilary heater was running when I arrived so I did an extra set while the aux heater was running.

This is where I need a set of healthy reading from a year ago. (-:

 

[manfrotto]

I had a similar issue on my Audi Q3, and was pretty sure it was a faulty thermostat for the DSG cooler as you suspect.
Unfortunately I sold the car before I changed it so cannot confirm fo r sure though.

 

[mmi]

Thanks for the reply

At 19% the fan is physically running. As you said if you turn it off with vcds it stops but says 10% in the measurable values.

So the car was sat cold in Garage I did the 2 sets of cold readings.
I drove first for Diesel when I pulled up Aux heater was running.
I then drove a 15-20minuet cross country loop to the super market, when I pulled up the heater was off. I did the Hot readings.
Then I drove home, the auxilary heater was running when I arrived so I did an extra set while the aux heater was running.

This is where I need a set of healthy reading from a year ago. (-:

Thanks. Nothing too obvious, all the units are at the same temperature, even Webasto aux.heater
You do have cabin heater ON at proper warm temperature, blower set to 2 or above?

I think we missed a controller which also plays as part of van's heat management - the 08-Climatronic AC.

Perhaps you could make a few more blockmaps, including 08-HVAC. Please set temperature to at least 22 °C, cabin blower at speed 2 or higher, air flow directed to windscreen, manual mode.

Blockmaps of controllers 01, 08, 18 at

A) COLD ENGINE OFF (ignition ON)​

B) COLD ENGINE IDLING

C) HOT ENGINE IDLING (after a 15+ minute drive, Stop/start off)​

 

[TALLANDREW]

thanks for looking I did the test again with the heater settings you said. sorry about the mass of files.

Do you see line 21_of the warm engine HVAC scan?



that would be malfunction coolant fan CPU?

 

[mmi]

Thanks again.
I can't find anything obviously wrong - as the logs were of 11 km journey in 12 minutes I'm not sure what kind of coolant temperature rise we can expect. Below a log of mine at +10 °C ambient temperature.



I noticed that your DSG was at the same temperature as engine coolant on logs of 3rd January. However, the DSG was quite warm already at start-up. Mine seems to take forever (above T6-02...) to warm up.

Do you see line 21_of the warm engine HVAC scan?

that would be malfunction coolant fan CPU?

The "Malfunction" is the only value I have seen in this, though all my logs are from Climatic AC. Perhaps @Robert or @n10n can confirm how it's with Climatronic AC.

I noticed that the Fan is always on 19% Is that normal?

Do you have AC switched ON?

I am convinced that my fan CPU is broken

I'd like to believe that ECU would trigger a fault if the 19% wouldn't be a proper value at the moment.

 

[TALLANDREW]

Thanks for looking and providing the alternative data. AC was on. To be honest the van warmed up really fast in past even in the winter. The temperature starts warm because the van lives in the garage.



So you don’t think the malfunction is the Smoking gun?

I would conclude the order of attack would be

Replace three way valve which feeds the DSG cooler because my oil is warming too fast and possibly draining the heat from the coolant as described in the hella article. Also this is a cheaper part.

I don’t know if it’s possible but I was thinking I could try flashing the software on the fan control module with Odis to see if that helps. That’s how I would deal with a faulty home computer.

Final step would be to replace the fan control module.

 

[mmi]

So you don’t think the malfunction is the Smoking gun?

I'm afraid it's normal - at least with Climatic it is. Hope we will hear from Climatronic owners.

I don’t know if it’s possible but I was thinking I could try flashing the software on the fan control module with Odis to see if that helps.

I'm not sure how you could access the controller - it's not even shown as a submodule under ECU.

AC was on.

Perhaps you could check if having AC OFF would make a difference in radiator fan behaviour.

121-061

 

[TALLANDREW]

I‘m away for the week with my daughter I will get onto this when I get back.

Is the 7e0819809b the dsg cooler Temperatur regulator valve?

 

[TALLANDREW]

Just to update the thread. Took it to VW they diagnosed it as broken thermostat housing.

Basically the thermostat has to be seated correctly and while I was sure to align everything carefully and bought a good quality replacement it was not sitting right and so the engine didn’t warm up properly.

After replacing the housing with a housing and pre installed thermostat everything seems okay.

Fan is off and temperature rises steadily. The output temperature sensor on the radiator is just a few degrees up until the thermostat opens. Previously that was 30 degrees above the ambient temperature fairly quickly.

Anyway I made a video of the whole job which let’s be honest is a lot of work hopefully will save some others from making the same mistake.