Hi guys, first post for me this morning. Having bother with my coolant system and hope someone can help!

When I bought my 52 plate Octavia vrs the temp gauge was purely decoration, no worky at all. Luckily the previous owner had supplied a new CTS(green) and thermo which I have now fitted. The themo has been aligned as the old one came out and the system bled (top cap off, heaters on, allowing the fans to come on and off a few times).

At first, this seemed to be sorted. The car warmed up to 90 after 5-10 mins and fuel economy improved dramatically.

The other day, coolant warning light. Checked the level and restarted the car, all gone. Then, what I can only assume is limp mode(never experienced it before!), car wouldn't rev past 2.5k. Once again, restarted car, all sorted.

Now, the temp gauge is taking far longer to heat up and won't go past 80-85. No warnings or anything though, car is running fine.

I'm thinking about doing a full coolant flush and bleed to see if this helps but outside that I have no idea! My neighbour works for vag and air lock is all he can suggest.

Anyone have any ideas?

Cheers.

Do you know if the cts and stat were genuine? Not impossible for non gen ones to cause problems pretty quick, especially if they've been rattling around in someone's bits draw. Your symptoms sound like they could be more related to the sensor, but to be on the safe side I would consider changing both. Could be an airlock as well which confused the issue but after running and checking levels for a few days I would think that would be settled by now.

Could be something else, but not sure what, I'd probably try a genuine cts first.

Genuine VAG CTS is a must.

Did you put in a new thermostat seal? Check for coolant leak around the thermostat housing.

Plus it may be there but not seated properly.

Thanks for all the replies! Wasn't expecting so many folks to help out so quick!

I would doubt that the parts were genuine, going from the maintenance level of the car in general.

Think I'll do a check on the thermo seal when the system is refilled to eliminate that, as the car did seem to spit out a bit of coolant on first starting. Then a genuine vag CTS if still happening. That way I can remove the possibility of it being my terrible mechanical skills at fault! = )

Thanks again all!

Oh, and yes I did put a new seal in. But I wouldn't be surprised if it isn't sitting quite right. It's an absolute bugger to get at.

Oh, and yes I did put a new seal in. But I wouldn't be surprised if it isn't sitting quite right. It's an absolute bugger to get at.

I needed mine doing when the weather was bad with a capital B, so I got my mechanic mate to do it at the local, he didn't get the O ring seated right first time...

That makes me feel a bit better then! I asked my usually very eager to help neighbour (vw mech for 27 years) if he would give me a hand with it initially. Before I'd even finished the sentence he told me I was on my own with that job. = )

That's nice of him lol. It's quite straightforward it's just awkward to get to if you haven't simplified any pipework.

Just FYI if anyone finds this while troubleshooting. It was the cheap CTS, dang thing never worked properly out of the box. Put a meyle one on it and everything now works perfectly. Chalk one more up for the "buy cheap, buy twice" mantra. Chers.

Well done for sorting out the problem.