Coolant temp sensor/gauge intermittent

MickAli

MickAli

Member
United-Kingdom
So I went on a long 600m round trip and the temp gauge dropped to zero a few times during the journey.
I have run to work today after plugging in VCDS (there are no fault codes in engine module) and monitored the coolant temperature. This rose gradually as expected and when it achieved 102degrees on VCDS screen the dash gauge then came straight up to 90 (it didn't move till then).
The gauge hasn't dropped so far today so I couldn't see what VCDS would say if it did. I will be checking and cleaning connections on day off, but till then.
Questions:
1. Which coolant sensor sends the signal to ecu, the G62 or G83? Which one is VCDS reading? I only ask as the gauge didn't move till 90degrees
2. Is it normal for the gauge to move from zero straight to 90 rather than climb gradually?
3. Is this a known/common issue

Cheers
Mick
 
MickAli said:
So I went on a long 600m round trip and the temp gauge dropped to zero a few times during the journey.
I have run to work today after plugging in VCDS (there are no fault codes in engine module) and monitored the coolant temperature. This rose gradually as expected and when it achieved 102degrees on VCDS screen the dash gauge then came straight up to 90 (it didn't move till then).
The gauge hasn't dropped so far today so I couldn't see what VCDS would say if it did. I will be checking and cleaning connections on day off, but till then.
Questions:
1. Which coolant sensor sends the signal to ecu, the G62 or G83? Which one is VCDS reading? I only ask as the gauge didn't move till 90degrees
2. Is it normal for the gauge to move from zero straight to 90 rather than climb gradually?
3. Is this a known/common issue

Cheers
Mick
Click to expand...
Which engine?
Mac.
 
Good Morning,

In future please state engine code when posting it saves everyone looking up what you have in 'About'. (Applies to everyone!).

The temperature engine outlet sensor is G62 but you would have known that if you had been using the in-house VCDS download add-in published recently, suggest you read the thread.

FSI ECU VCDS Label File Add-In Download

Attached something never before available to my knowledge¹, a VCDS label file for the FSI ECU in English. This file can be used with all versions of VCDS, Lite (Registered or Unregistered) or Full. Prior to this point the text that appears with FSI VCDS ECU Measuring and Basic Settings groups...
www.a2oc.net www.a2oc.net

1685619324729.png


From what you describe with gradual warm up from cold reaching 102℃ sounds normal. If you want some comparative warm up data read this

A Slightly Geekish Look At FSI Coolant Warm-up

Only read if interested! Currently I am involved in constructing a label file for the FSI ECU, a small portion of which is the coolant groups 130-137 and along with my contributions to Evros's current coolant thread I have have become intrigued with FSI coolant warm-up, how it behaves and what...
www.a2oc.net www.a2oc.net

No, the coolant gauge should not jump to 90℃ but rise gradually with temperature over a ten minute period. This sounds to me like the temperature sensor output side for the dash gauge is failing while VCDS is reporting the other side for the ECU is working normally. With VCDS you can monitor both sides of the sensor outputs for comparison and then make a decision about sensor replacement. Please post the actual VCDS reports if possible if you do.

Andy
 
Last edited:
Could also be a dash issue with the gauge motor or connections. Sensor could be supplying the value but gauge not reacting.
 
Andrew said:
Good Morning,

In future please state engine code when posting it saves everyone looking up what you have in 'About'. (Applies to everyone!).

The temperature engine outlet sensor is G62 but you would have known that if you had been using the in-house VCDS download add-in published recently, suggest you read the thread.

FSI ECU VCDS Label File Add-In Download

Attached something never before available to my knowledge¹, a VCDS label file for the FSI ECU in English. This file can be used with all versions of VCDS, Lite (Registered or Unregistered) or Full. Prior to this point the text that appears with FSI VCDS ECU Measuring and Basic Settings groups...
www.a2oc.net www.a2oc.net

View attachment 108728

From what you describe with gradual warm up from cold reaching 102℃ sounds normal. If you want some comparative warm up data read this

A Slightly Geekish Look At FSI Coolant Warm-up

Only read if interested! Currently I am involved in constructing a label file for the FSI ECU, a small portion of which is the coolant groups 130-137 and along with my contributions to Evros's current coolant thread I have have become intrigued with FSI coolant warm-up, how it behaves and what...
www.a2oc.net www.a2oc.net

No, the coolant gauge should not jump to 90℃ but rise gradually with temperature over a ten minute period. This sounds to me like the temperature sensor output side for the dash gauge is failing while VCDS is reporting the other side for the ECU is working normally. With VCDS you can monitor both sides of the sensor outputs for comparison and then make a decision about sensor replacement. Please post the actual VCDS reports if possible if you do.

Andy
Click to expand...
Apologies, I knew I'd forgotten something. It's an FSI. Unfortunately I currently only have unregistered VCDS lite so don't have measuring blocks beyond group 25 so just using group 001 for basic temp
 
Andrew said:
Good Morning,

In future please state engine code when posting it saves everyone looking up what you have in 'About'. (Applies to everyone!).

The temperature engine outlet sensor is G62 but you would have known that if you had been using the in-house VCDS download add-in published recently, suggest you read the thread.

FSI ECU VCDS Label File Add-In Download

Attached something never before available to my knowledge¹, a VCDS label file for the FSI ECU in English. This file can be used with all versions of VCDS, Lite (Registered or Unregistered) or Full. Prior to this point the text that appears with FSI VCDS ECU Measuring and Basic Settings groups...
www.a2oc.net www.a2oc.net

View attachment 108728

From what you describe with gradual warm up from cold reaching 102℃ sounds normal. If you want some comparative warm up data read this

A Slightly Geekish Look At FSI Coolant Warm-up

Only read if interested! Currently I am involved in constructing a label file for the FSI ECU, a small portion of which is the coolant groups 130-137 and along with my contributions to Evros's current coolant thread I have have become intrigued with FSI coolant warm-up, how it behaves and what...
www.a2oc.net www.a2oc.net

No, the coolant gauge should not jump to 90℃ but rise gradually with temperature over a ten minute period. This sounds to me like the temperature sensor output side for the dash gauge is failing while VCDS is reporting the other side for the ECU is working normally. With VCDS you can monitor both sides of the sensor outputs for comparison and then make a decision about sensor replacement. Please post the actual VCDS reports if possible if you do.

Andy
Click to expand...
Andy,
Many thanks for the tips. I did read the warm up and Add-in threads which helped. My first thought was a signal issue and checking connections is first port of call.
I have seen recommendations to only use genuine sensors (if I end up changing G62) but I have found an OE spec Febi one and I usually find Febi are very good quality. Thoughts?
Mick
 
MickAli said:
Andy,
Many thanks for the tips. I did read the warm up and Add-in threads which helped. My first thought was a signal issue and checking connections is first port of call.
I have seen recommendations to only use genuine sensors (if I end up changing G62) but I have found an OE spec Febi one and I usually find Febi are very good quality. Thoughts?
Mick
Click to expand...
Yes, sensors from Audi is the recommended way to go and Febi is a respected brand. I do not know who supplies Audi and from memory there is nothing on the sensors to indicate. Why not PM Tom at Crewe Audi on here and ask for a quote it would be good to know but it will boil down to cost versus risk, your call but I would buy from Audi.

Consider upgrading to registered Lite.

Andy
 
Andrew said:
Yes, sensors from Audi is the recommended way to go and Febi is a respected brand. I do not know who supplies Audi and from memory there is nothing on the sensors to indicate. Why not PM Tom at Crewe Audi on here and ask for a quote it would be good to know but it will boil down to cost versus risk, your call but I would buy from Audi.

Consider upgrading to registered Lite.

Andy
Click to expand...
I second Andy's recommendation, register your Lite, it could save you the $99 in parts very quickly.
I know I'm biased, but if you intend to run your FSI long-term, then you really should.
Mac.
 
If its the green one that had 2 separate circuits one supplies the ecu and therefore fueling the other the dash for your convenience. Would be wise to replace the sensor
 
Had a good look around. Found the G83, cleaned connections and got a DTC which i cleared, so that's ok. Same with the G265 thermostat one.
Now I can't find the G62 anywhere. Not top hose, Rad.
Can someone tell me where it is on an FSI?
 
MickAli said:
Had a good look around. Found the G83, cleaned connections and got a DTC which i cleared, so that's ok. Same with the G265 thermostat one.
Now I can't find the G62 anywhere. Not top hose, Rad.
Can someone tell me where it is on an FSI?
Click to expand...
G62 is "plugged in" the thermostat housing (sometimes called the coolant distributor) next to the engine outlet flow. The large pipe just below the green sensor is the the flow pipe to the radiator.
1685710960919.png


It is well buried. There is a description of removal in the workshop guide but Sarge's 'How To' is just as good.

Sarge's A2 Servicing Information

21 Removing Interior Heater Fan Motor Fault: No heater fan motor action, the fan speed indication on the climate control may show increasing bars then drop down to one bar but fan doesn't work. This usually is the fault with the heater fan motor and to replace it is as below. Disconnect car's...
www.a2oc.net www.a2oc.net

Andy
 
Andrew said:
G62 is "plugged in" the thermostat housing (sometimes called the coolant distributor) next to the engine outlet flow. The large pipe just below the green sensor is the the flow pipe to the radiator.
View attachment 108775

It is well buried. There is a description of removal in the workshop guide but Sarge's 'How To' is just as good.

Sarge's A2 Servicing Information

21 Removing Interior Heater Fan Motor Fault: No heater fan motor action, the fan speed indication on the climate control may show increasing bars then drop down to one bar but fan doesn't work. This usually is the fault with the heater fan motor and to replace it is as below. Disconnect car's...
www.a2oc.net www.a2oc.net

Andy
Click to expand...
Clearly couldn't see the wood for the trees! Cheers
 
You must log in or register to reply here.
Back
Top