Hello, I think I am not alone as regards the issue I am having with my Skoda Yeti Diesel 4x4 2L 2013 model. I noticed recently that the engine temp gauge was varying.  It has sat steady at 90 since I bought the car second hand 4 years ago. After a long run on the motorway just before Christmas I noticed the temp dropping at tick-over to eventually to 70. It also varied between 70 and 90 on local running. I took it to my local garage , who have sorted any previous issues out I had without  problem. They diagnosed a faulty temperature sensor and replaced it with a genuine VAG part. It seemed to improve the situation, but the temperature still would vary, now between 90 whilst driving on faster roads and then gradually dropping to 80 at tick-over when stationary. Short runs it will vary between 90 and 80 with no obvious reason. The same garage have recently had the car in again to check further and could find no problem with the thermostat and apologised that they could not find a reason why the car was behaving this way. They also checked all the other possible other causes for this anomaly at the first visit.  The heaters work fine at full heat and the only obvious problem seems to be the fluctuating temp gauge, which does not vary despite how the heater is set. The car has no DSG so the 'secondary' thermostat' is not fitted ( I am told). I just wondered if anyone has any experience of a similar fault and is aware of a fix. I have been assured there is no detriment to the running of the car, so am I being overly concerned?

Welcome!

 

When I had similar issues on a 2012 Octavia CR140 - it was the main thermostat failing and a replacement fixed it

 

I logged the temperatures before/after to confirm the issue/fix:

 

 

Another member also had success with a new thermostat too. Seems like it's an arse of a job, the dealer had my car for an entire weekend to fit it!

 

Hello, thanks for that so I may have an issue with the thermostat?

Your symptoms match mine so it's my best guess 

- I had no issues with heater output

- I noticed the oil temp would sit around 80-85'C rather than 90'C+ at a continuous 60-70mph

- When the weather dropped cooler, I saw the same water temp drop that you've described when stationary

 

If your oil temps are also low like mine that suggests both your temperature sensors are reading correctly. If so the engine is probably overcooling which is likely the thermostat

 

I'm sure some others will be along soon who may have some alternative suggestions.

Hello, thank you I was told by the garage that the thermostat was ok. I do trust them, however I am just concerned that it still may be the thermostat based on what I have read on various forums. I understand it can be quite a job to change it, so I don't like saying it as they are very helpful, but maybe it is not something they were willing to tackle without being sure of success? I wondered if it is the first signs of it failing?? Again thanks for your input.

Hi IDC

 

The behaviour you describe is consistent with a thermostat that isn't completely closing. 

 

The temperature gauge has software between the sensor and the needle display, so that any temperature within say plus or minus 10 degrees of normal shows as a rock solid normal. That stops people worrying about minor fluctuations.  If your gauge is showing anything other than normal once fully warmed up, then something isn't right. 

 

The only exception to this would be in extreme conditions, e.g. if you descended a very long hill in freezing weather with the heater on full blast. In that case you might find that because you were taking out more heat than the engine was producing (from engine braking only) the temperature would eventually start to drop.

Thank you for taking time to reply. I am sure you are correct, based on what I have found out so far. It seems the thermostat should be investigated given the symptoms and previous work. Much appreciated

Did you ever resolve this?

On 12/01/2022 at 08:39, IDC said:

Thank you for taking time to reply. I am sure you are correct, based on what I have found out so far. It seems the thermostat should be investigated given the symptoms and previous work. Much appreciated

was this the final fix @IDC as I'm now experiencing the same issue and would be great to hear if a new thermostat resolved the issue....Thanks in advance :-)

IDC hasn't visited this forum since Jan 2022!