Krigepj

Good day to all

I am new to this site and am still finding my way around it. I have searched google and couple of sites to a solution to my problem, but no luck.
I started my car few days ago and noticed that something does not feel right and as it started getting to normal temperature the car lost more and more power, as if it is in limp mode. There is no fault on dash and nothing else indicating that something is wrong. I hooked it up to my VCDS and found one fault code which I can't find anywhere on the web.

8469 - Torque restriction due to coolant temperature P102A 00 [036]

The car does not overheat at all and the temperature stays at 90°C, but the car has no power. When it cools down it has bit more power, but not as it should and as soon as it starts warming up the power is gone again. Is there anybody out here that can shed some light on the subject for me please? I'm not willing to take my car the the dealer to keep replacing parts and keep paying tons of cash when they can't pin point what exactly is fault. The car is out of warranty and I know that parts on this car can get very expensive.

Thanks

nordicb

Hi there,

If you have VCDS, worth checking coolant temperature reading as engine management sees it. Dash gauge and engine management are likely to use different sensor circuits.

Let us know how you are getting on!

Krigepj

I did monitor the coolant temperatures, even as my wife was driving around and I sat in the passenger seat with the laptop on VCDS and all seems to increase slowly to normal temp.

nordicb

I see, perhaps there is an intermittent problem of some sort. If I recall correctly, open circuit would cause temperature reading to go down, and short circuit - up.
Does this fault have the freeze frame information, usually has date, mileage, rpm, coolant temp, etc data along with the fault itself. Does coolant temp look ok there too?

Krigepj

nordicb

Thanks. I think if you were driving for a while, say more than 5km, coolant here reads 66 degrees only. It means the engine never reached working temperature and management most likely remains in open loop. Open loop usually means some of sensors are ignored until engine reaches working temperature, which is 90 degrees on VAG engines. In open loop priority is given to heating up the engine quick, rather than emissions, correct mixture, etc. Generally, driving with low coolant temps is not good for the engine, but a lot of people do that.
If the temp rises while standstill, for example at traffic lights or town driving and drops on open roads, then it may indicate cooling system problem, like stuck thermostat, water pump or fancy coolant valves failure. Coolant sensor is usually cheapest and quickest to replace if needed.

Krigepj

The fault almost immediately comes on as you start driving the car and accelerate, but no fault as the car is idling before driving.

nordicb

I would try to search for "temp" in VCDS sensor list, perhaps you can trace down which sensor is not reading right. It's not one temp sensor, I believe, on this engine.

Krigepj

Thanks, I will try monitor all temp sensors.

Krigepj

Just to report that my issue is resolved. The G684 Engine head temperature sensor was faulty. I didn't add it to the VCDS list of sensors to monitor, but today I found it and added it and behold it was reading 141°C with cold engine. Bought a new sensor and everything back to normal and car is driving like a dream again.

Thanks to all for the advice.