Hi folks,

Had the clutch changed about 3 weeks back - last week I picked up a a strange issue with my IC. Have another Seat Sport member with the same symptoms.

On a cold start my car will get to 90 degrees before I am down my street(300m) - Engine is still cold though(I stopped, popped the hood and checked). Gauge is therefore registering incorrectly. If I switch the car off an on it will reset to 0 degrees on the gauge, about a km into the trip I hear a relay click by the fuse box and the temp gauge will rise again during the drive to 90 degrees in about a km or 2.

So I replaced the CTS with an oem one as well and it's still doing the same.

I then connected a VCDS cable, idled the car for 20 minutes and monitored. Temp will get up to around 96 degrees idling and stay there.
Fan came on and dropped the temps into the 80's. I know the gauge will stay at 90 during all this. if I switch the ignition off and immediately on, the gauge in the cluster will rise to close to 90 and drop to 0. Then same thing - after a minute a relay clicks and the gauge starts to register slowly and get up to 90.

I'm going to get the Thermostat changed next week as the car is 9 years old, a few guys said change the thermostat and see. Wondering if anyone experienced this before?

Are there not 2 temp sensors, 1 near the radiator outlet (controlling the fan) and one on the head water flange (signal for the gauge)?

Seems to only be 1 on the BBU? 2 Pin version sending signal to ECU and to the gauge separately.
I'm going to have the thermostat changed but I'm not so sure it will solve the issue, seems more electrical to me.

Correct Theres only one CTS , on the right of head.

Agreed that it doesn't sound like an issue with the thermostat as a faulty thermostat symptoms differs from what you experiencing

ICE King wrote: ↑Tue Jul 10, 2018 4:38 pm Correct Theres only one CTS , on the right of head.

Agreed that it doesn't sound like an issue with the thermostat as a faulty thermostat symptoms differs from what you experiencing

No harm in changing the thermostat anyway - It's 9 years old. Never been changed.
Yeah, thermostat symptoms are different.

Also even on hot start the car idles higher(closer to 1000rpm) for 30 secs to a minute. Even if I switch off and immediately on.
These little niggles are such a pain to find. I suspect a dodgy earth or sensor plug pin? Any way to check this?

Could also be the new sensor is faulty out the box, possibly giving same/similar issue? Maybe test with a known working one from another car?

MarshallGTi wrote: ↑Tue Jul 10, 2018 5:08 pm Could also be the new sensor is faulty out the box, possibly giving same/similar issue? Maybe test with a known working one from another car?

Could be, but what are the chances a brand new OEM one would have the exact same issues as the old one?
Same side of sensor giving issues. But worth a shot checking I guess hey!

Actually quite good, myself and other 20v owners have had this exact issue, it is definitely the CTS even from vw it seems like a lucky packet

SoDub wrote: ↑Tue Jul 10, 2018 4:52 pm

ICE King wrote: ↑Tue Jul 10, 2018 4:38 pm Correct Theres only one CTS , on the right of head.

Agreed that it doesn't sound like an issue with the thermostat as a faulty thermostat symptoms differs from what you experiencing

No harm in changing the thermostat anyway - It's 9 years old. Never been changed.
Yeah, thermostat symptoms are different.

Also even on hot start the car idles higher(closer to 1000rpm) for 30 secs to a minute. Even if I switch off and immediately on.
These little niggles are such a pain to find. I suspect a dodgy earth or sensor plug pin? Any way to check this?

Agreed change the thermostat anyway since its dated.

As suggested find someone with a known working CTS , swop it out and take it from there. #20valve problems

SoDub wrote: ↑Tue Jul 10, 2018 5:25 pm

MarshallGTi wrote: ↑Tue Jul 10, 2018 5:08 pm Could also be the new sensor is faulty out the box, possibly giving same/similar issue? Maybe test with a known working one from another car?

Could be, but what are the chances a brand new OEM one would have the exact same issues as the old one?
Same side of sensor giving issues. But worth a shot checking I guess hey!

Hence why all spares regardless off OE or aftermarket it states no warranty on electric parts. Its cr@p but it is what it is...

MarshallGTi wrote: ↑Wed Jul 11, 2018 11:12 am

SoDub wrote: ↑Tue Jul 10, 2018 5:25 pm

MarshallGTi wrote: ↑Tue Jul 10, 2018 5:08 pm Could also be the new sensor is faulty out the box, possibly giving same/similar issue? Maybe test with a known working one from another car?

Could be, but what are the chances a brand new OEM one would have the exact same issues as the old one?
Same side of sensor giving issues. But worth a shot checking I guess hey!

Hence why all spares regardless off OE or aftermarket it states no warranty on electric parts. Its cr@p but it is what it is...

For over R600 for the sensor I will change their returns policy. Luckily the workshop is part of GW so they can make a plan!

Had the thermostat done last week and all is back to normal- Phew!. They checked the wiring and the new CTS and it was all perfect. So strange the thermostat was causing the gauge to act like that!