A3 8p temperature issue

Slowroger · Oct 19, 2017

Hi all,

I have an Audi A3 2.0 TFSI Quattro 2004 with 111,000 miles on the clock - I have had it fully serviced this week and the MOT passed 2 months ago with no faults or advisories.

I've noticed the engine when driving takes forever to heat up and won’t hit 90 degrees centigrade, but if I let the car sit and idle it will reach 90c.

When driving from 90c onto a motorway the gauge shows the temperature to drop down to quarter, so roughly about 70c. I cannot hear the engine fans running when this is happening.

This week I had both the thermostat and the coolant temperature sensor replaced. Prior to the thermostat being replaced the engine fans would come on straight away on ignition and at random intervals - this does not happen since having them replaced. Coolant levels are what they should be as well. The only error code returned was stating the original coolant temperature sensor was faulty.

Note that before having the thermostat changed, the car would never reach 90c at idle, it now does from the replacement

When I turn on the car heating to the max, the air feels lukewarm at best even when the engine says its 90c - When I turn the heating on though, I can see the temperature gauge start to drop until I turn the heating back off again.

The car runs fine and never over heats.

Any help is fully appreciated.

LEE69 · Oct 19, 2017

Did you have a genuine stat fitted?
Pattern parts have been known to fail very quickly

Slowroger · Oct 19, 2017

Hi yeah genuine thermostat I purchased from TPS myself.

LEE69 · Oct 19, 2017

Only one reason why it doesn't hold temp, is the stat. Also not sure if there are 2 CTS on these ?

Slowroger · Oct 19, 2017

Not sure on that one, I was under the impression just the one. I'm not overly convinced it's still the thermostat as a lot of signs vanished when I had it replaced - I.E fans coming on full force on cold ignition and then at random intervals and the engine can now reach 90c.

The garage couldn't even figure it out. I wanna avoid doing so as costy but perhaps an Audi specialist is the next thing. Really hoping can diagnose from here though.

LEE69 · Oct 19, 2017

Mobzor said:
Not sure on that one, I was under the impression just the one. I'm not overly convinced it's still the thermostat as a lot of signs vanished when I had it replaced - I.E fans coming on full force on cold ignition and then at random intervals and the engine can now reach 90c.

The garage couldn't even figure it out. I wanna avoid doing so as costy but perhaps an Audi specialist is the next thing. Really hoping can diagnose from here though.

It's reaching 90 but not holding when heater fans on is it dropping when coasting using no throttle? Down a bill is a good test

Posted using a S8+ with Magic

LEE69 · Oct 19, 2017

LEE69 said:
It's reaching 90 but not holding when heater fans on is it dropping when coasting using no throttle? Down a bill is a good test

Posted using a S8+ with Magic

Hill not bill lol

Posted using a S8+ with Magic

Slowroger · Oct 19, 2017

LEE69 said:
It's reaching 90 but not holding when heater fans on is it dropping when coasting using no throttle? Down a bill is a good test

Posted using a S8+ with Magic

Uhh I do have a bad habit of coasting up to junctions, but in this instance the temp drops when driving normally. However having said that, I haven't tested coasting down a hill with the heating on lol. I'll test it out as soon as I get a chance!

Slowroger · Oct 19, 2017

Ok so I coasted down a hill with heating on - there was no difference to normal driving here it dropped the same.

NHN · Oct 19, 2017

Is the coolant circulating would be my 1st check.

Feel all pipes in the system, if not all boiling hot then its got a lock & that is due to the work, ideally when I drain down mine, I leave cap of & standing over night in case of, never had an issue.

Slowroger · Oct 19, 2017

I'll give the pipes a feel later when I get the chance to try and warm the car up.

Quick bit of research says if I take the coolant lid off and run the engine idle for about 20 mins that should clear it? Anything else you can reccomend? Its only recently in the past week been changed with my cam belt and water pump, so don't wanna drain it.

ahtcap · Oct 19, 2017

Mobzor said:
I'll give the pipes a feel later when I get the chance to try and warm the car up.

Quick bit of research says if I take the coolant lid off and run the engine idle for about 20 mins that should clear it? Anything else you can recommend? Its only recently in the past week been changed with my cam belt and water pump, so don't wanna drain it.

Keep squeezing the rubber pipes whilst doing this.

Slowroger · Oct 19, 2017

Ok so I let it idle for 20 minutes or so until it hit 90 degrees with the coolant cap off - Was giving the coolant pipe a squeeze and could see it throwing some back into the reservoir but due to the angle couldn't tell if bubbles were coming out. I put my heating on full and the temp gauge dropped to just below quarter and the radiator fan went on full whack. Not really hot hot air coming through when the gauge said 90c.

Not convinced it did anything to be honest.

Fan control module perhaps? Just ordered one of those OBD2 adapters so will check for any new error codes. Not sure there will be as the garage only detected the coolant temperature sensor giving a fault and replaced it.

Slowroger · Oct 21, 2017

Further testing this so far, coasted down a long piece of road and the temperature went up, when in touch the throttle it drops down again.

Scanned for errors with my obd2 tool and only one given is my turbo boost sensor error A circuit high PO238

I have no idea now.

s5joe · Oct 21, 2017

sounds like its got a air lock in there to me i try drawing it and refilling it

Slowroger · Oct 21, 2017

s3joe said:
sounds like its got a air lock in there to me i try drawing it and refilling it

Any other ways I can bleed the air out rather than drain and re-fill? Already tried running idle for 20 mins with the cap off and squeezed the coolant pipes. Mega keen to cure this as it really bugs me.

Slowroger · Oct 25, 2017

Just gonna bump this one -

Also discovered the radiator fan goes comes on to full power when I put the heating onto maximum - Is that normal?

The coolant temperage then drops to 60c.

aqibi2000 · Oct 27, 2017

Borrow a friends MAF, my car would take decades to warm up.

Borrow for a few days.

Slowroger · Oct 28, 2017

Hi all.

I fixed this problem by removing the bumper and screwing some 3mm acrylic plastic sheets to yhr bottom half of my grill below the reg plate.

Temperature gets to 90c and only drops to 80c on the motorway. May do a little part of the upper grill and see if it consistently holds 90c or a few below.

I feel it's like I've put a plaster on it lol. But will monitor the temperature closely, may even need to remove for next summer, we'll see.

Thanks for the suggestions in here.

A3 8p temperature issue

A4 S-line Black Edition Quattro

07 170 DSG

A4 S-line Black Edition Quattro

07 170 DSG

A4 S-line Black Edition Quattro

07 170 DSG

07 170 DSG

A4 S-line Black Edition Quattro

A4 S-line Black Edition Quattro

Retrofitter - Audi - VW - Skoda - Seat

A4 S-line Black Edition Quattro

Registered User

A4 S-line Black Edition Quattro

A4 S-line Black Edition Quattro

Registered User

A4 S-line Black Edition Quattro

A4 S-line Black Edition Quattro

Registered User

A4 S-line Black Edition Quattro

Similar threads