Hi Mikek3111

 

Ambient temp sensor seems to show correct temperature on dash...

 

 

Have a look at this - shows the location of the tempertaure sensor. They are really easy to replace, like bulb easy, and cost buttons to buy. You will loose some coolant in the process, so have a litre or two to top up once replaced. Best done on a cold engine to avoid scalding yourself.

 

 

 

Cheers for that Westbury63 ....looks slightly different than what I remember when i took air box out to do the radiator sensor which should have been an easy job but Clip that held it in was metal and just fell apart when I tried to remove it and took a while to dig it out...lol 

 

Atleast i roughly know where to look now so thanks for sending video clip

On 02/06/2019 at 16:39, silverback1972 said:

I had the same symptom ( not saying it's the same fault) with my MK 2 Octavia. The fan would come on within 5 mins of starting  and revs would go up, fuel economy went South. It turned out to be a dodgy DPF sensor. Even though the DPF light didn't come on the car kept going into regen mode. Sensor changed and it fixed the issue. 

Hi. Did this not show up as a fault code? As my fan comes on and the revs go up to around 1k after starting the car every morning, and the engine is a bit rough for a while. It seems to drive better later in the day, but it can do the same thing with the fan & revs. 

The engine management light came occasionally and that pointed to the sensor but the fault occured many times without the light coming on. 

26 minutes ago, silverback1972 said:

The engine management light came occasionally and that pointed to the sensor but the fault occured many times without the light coming on. 

Ok, thanks for the reply I've had no lights come on

1 hour ago, Tezza2020 said:

Hi. Did this not show up as a fault code? As my fan comes on and the revs go up to around 1k after starting the car every morning, and the engine is a bit rough for a while. It seems to drive better later in the day, but it can do the same thing with the fan & revs. 

Do you have a DPF on your engine ?

 

If so, it sounds like the classic characteristics of the ECU trying to instigate a regen of the DPF.

 

If you've been doing lots of short journeys it probably hasn't been able to complete a regen.

 

Take the car on a longer run next time you use it ( probably 10 miles will be enough ).

 

If the fans are off when you get home the regen will have completed.

2 minutes ago, PipH said:

Do you have a DPF on your engine ?

 

If so, it sounds like the classic characteristics of the ECU trying to instigate a regen of the DPF.

 

If you've been doing lots of short journeys it probably hasn't been able to complete a regen.

 

Take the car on a longer run next time you use it ( probably 10 miles will be enough ).

 

If the fans are off when you get home the regen will have completed.

Hi. I do yes. I do regular long journeys. And short journeys. But this doesn't seem to improve the fault. This engine only has one main fan btw.

My Octi had an issue with fan, what worked all the time, changed yesterday the relay under the battery tray, problem solved, a lot of video on YouTube about this common issue. When you have any problems with the fans, you need to change, not a big deal when the bolt is not rotted, than you need to remove with saw blade

Relay number: 1j0919506k

Edited 24 November, 20241 yr by miofan

Just added more info why fan capable to go bad, I had an issue with coolant temp sensor, cause the temperature not hold the 90 Celsius, tried couple of sensors, nothing changed, than someone told me to change the thermostat and problem solved. Now I know, I will change every recommended 50k km the thermostat and the plastic holder. You can not remove without breaking little parts what are holding the thermostat with rubber sealing. More easy to change both of them and they are very cheap.