[STIPER2]

Hi,
Been a while since I have been here. Originally I had a "Check Engine light fault come on every time the outside temp went below 20 degrees and stayed that temp. Once it rose above the light would go off on its own. Never did find out what was wrong with it, replaced everything the VW dealer could including an new EMC. I think thats what its called . The brains to the car. I have since moved to Arizona and will not have to worry about it coming on anymore.
My new concern is that after I have driven the car 3 to 5 miles and turn it off it smells warm, like rubber, coolant getting hot, So I popped open the hood while it was running and I noticed the 2 fans for the radiator were not running at all while the car was on. As soon as I turned it off, about 5 mins later they kicked on for a few mins and shut off. Now it was a mild day here for AZ, about 70 degrees. Is this typical for this car or is there an issue with the cooling system? I don't drive the car much. Its a Sunday type car. Any input from the experienced VW owners would be appreciated.
Thanks
Don

 

[voxmagna]

You don't say what year car? Early model V.W engines used a common simpler design cooling system. When the engine has been running up to temperature and then stopped, the water pump stops circulating and the cylinder head can get large cycles of overheating, never been a problem on MY07. They also started putting fans on to purge the engine bay of rising hot air from the CAT and exhaust. We have another newer VAG car (not EOS) that has an auxiliary electric water pump. When this car is parked & key out after a drive, you can hear a small noise from the front then both fans come on for about a minute or two and go off. During this time coolant is circulated and cooled by engine fans. This behaviour starts very soon after turning off the key in hotter weather or may start a minute later when the temperature sensor sees the rise in temperature. They also wanted to purge the engine bay of hot air after stopping (another sensor?) an ECU for an early model will have different functionality compared to a later model ECU. It's worth getting a genuine V.W dealer to check the ECU version fitted against your VIN number to make sure it has the correct firmware version? IMHO replacing an ECU is the last thing I would have done and I would have kept the original.

With what has happened to you before and given the seriousness of a possible cooling fault, I think you should look a bit deeper because hot rubber smell doesn't smell right? Find out if your model engine uses an auxiliary electric coolant pump and you have the newer system I explained? Both fans are coming on so you don't have a fan fault, but you need to know if they are doing the right thing at the right time? You say the ECU was changed? Engine cooling (not necessarily the dash gauge) is often controlled by a dedicated temperature sensor fitted to the cylinder head. This is also used by the ECU to adjust engine fuelling and cold weather fuelling (aka choke). I would expect the ECU to be matched to that sensor and you had the ECU changed?

Using diagnostics real time measurement, the engine temperature readout can be monitored whilst the engine warms up on idle on a hot day. After 10-15 minutes, fans should cut in and the temperature should be in spec, (usually somewhere about 100 degC). You watch the temperature whilst the fans are on and it should start falling until they go off (about 80 deg.C). You can look at the gauge whilst doing this, but it may not show the same temperature. If temperature falls too slowly (or keeps rising!) with fans on, your system has a bad radiator or air locks. With your problem it's important to use a digital thermometer inserted in a hose near the top of the engine to confirm the temperature which the ECU sees is about the same as the digital themometer. If there's a big difference, suspect the temperature sensor & ECU combination. You can't get a diagnostics readout of engine temperature with ignition off, but the digital thermometer should show you whether the rise in temperature is being reduced by an auxiliary electric pump if fitted.

 

[STIPER2]

You don't say what year car? Early model V.W engines used a common simpler design cooling system. When the engine has been running up to temperature and then stopped, the water pump stops circulating and the cylinder head can get large cycles of overheating, never been a problem on MY07. They also started putting fans on to purge the engine bay of rising hot air from the CAT and exhaust. We have another newer VAG car (not EOS) that has an auxiliary electric water pump. When this car is parked & key out after a drive, you can hear a small noise from the front then both fans come on for about a minute or two and go off. During this time coolant is circulated and cooled by engine fans. This behaviour starts very soon after turning off the key in hotter weather or may start a minute later when the temperature sensor sees the rise in temperature. They also wanted to purge the engine bay of hot air after stopping (another sensor?) an ECU for an early model will have different functionality compared to a later model ECU. It's worth getting a genuine V.W dealer to check the ECU version fitted against your VIN number to make sure it has the correct firmware version? IMHO replacing an ECU is the last thing I would have done and I would have kept the original.

With what has happened to you before and given the seriousness of a possible cooling fault, I think you should look a bit deeper because hot rubber smell doesn't smell right? Find out if your model engine uses an auxiliary electric coolant pump and you have the newer system I explained? Both fans are coming on so you don't have a fan fault, but you need to know if they are doing the right thing at the right time? You say the ECU was changed? Engine cooling (not necessarily the dash gauge) is often controlled by a dedicated temperature sensor fitted to the cylinder head. This is also used by the ECU to adjust engine fuelling and cold weather fuelling (aka choke). I would expect the ECU to be matched to that sensor and you had the ECU changed?

Using diagnostics real time measurement, the engine temperature readout can be monitored whilst the engine warms up on idle on a hot day. After 10-15 minutes, fans should cut in and the temperature should be in spec, (usually somewhere about 100 degC). You watch the temperature whilst the fans are on and it should start falling until they go off (about 80 deg.C). You can look at the gauge whilst doing this, but it may not show the same temperature. If temperature falls too slowly (or keeps rising!) with fans on, your system has a bad radiator or air locks. With your problem it's important to use a digital thermometer inserted in a hose near the top of the engine to confirm the temperature which the ECU sees is about the same as the digital themometer. If there's a big difference, suspect the temperature sensor & ECU combination. You can't get a diagnostics readout of engine temperature with ignition off, but the digital thermometer should show you whether the rise in temperature is being reduced by an auxiliary electric pump if fitted.

The year is a 2012 with 77,000 miles. When I was having this "Check Engine Light" issue it was in a VW shop (dealership) for the repair. I went to this specific shop due to they had 3 mechanics there that new the Eos Mechanics pretty well. They called in special techs from VW to work on the issue. They never could find the source causing the light to come on. Everything in the car operated as it should, just the light came on when temp outside got below 20 degrees.
Now back to the radiator, its not overheating so I think that says something? They car has always had the proper maintenance done.
Maybe next time I take it out to run the cobwebs out of it I take it for a bit longer drive and at that point stop and check to see if the fans are coming on. If not I will get it checked out.

 

[STIPER2]

The year is a 2012 with 77,000 miles. When I was having this "Check Engine Light" issue it was in a VW shop (dealership) for the repair. I went to this specific shop due to they had 3 mechanics there that new the Eos Mechanics pretty well. They called in special techs from VW to work on the issue. They never could find the source causing the light to come on. Everything in the car operated as it should, just the light came on when temp outside got below 20 degrees.
Now back to the radiator, its not overheating so I think that says something? They car has always had the proper maintenance done.
Maybe next time I take it out to run the cobwebs out of it I take it for a bit longer drive and at that point stop and check to see if the fans are coming on. If not I will get it checked out.

I did keep the original ECU.

 

[voxmagna]

I'm just giving you a toolkit of suggested actions for you or somebody else to work through for a proper diagnosis or re-assurance. If you get to the end and all the boxes are ticked, I'd say your cooling system was probably o.k. If you go on a long journey ignorant of what's happening or not and something bad happens, then it's to late to go back.

I did keep the original ECU

Well that's something. Diagnostics can read the fitted ECU header to get type and firmware information, the original ECU is fairly easy to put back for a scan test and unless it's completely faulty (car won't start) you can get that read and compare the two? I bet that ECU is o.k, but once they order it up from V.W, open the sealed bag and try it, they have to charge you for it.

You say your radiator isn't overheating but you don't know if it's lost efficiency? Doing what I suggested will tell you that. You can wait until the hottest summer day, idle the car after a drive and if the fans don't go off for a very long time, you will have an answer - poor cooling system efficiency?

They never could find the source causing the light to come on.

Every CEL on event is backed up in the fault log. The problem is they didn't know how to analyse the fault code and determine what was causing it! This can happen with intermittent problems, but knowing the fault codes they should have gone further and used their diagnostics to assess the performance of the cooling system. Even if they were working blind, they could have taken a gamble and checked thermistor temperature sensors and wiring.

If you don't want to do any further investigation or checks, that's another strategy which may eventually lead to a more obvious fault. You could be relying on V.W engine self protection after a CEL comes on to warn you or it stops your engine to protect itself.

You seem to have convinced yourself that 20C below is cooling system related? But there are other more important temperature dependent parts to an Efi engine - e.g MAF sensor. When you put your trust in others and can't do anything yourself, you have no choice but to rely on them. Now you've moved, you can't keep going back to complain about the same fault so you either put up with it and wait for something more obvious to happen, or start the journey again with a new local dealer?

 

[STIPER2]

I'm just giving you a toolkit of suggested actions for you or somebody else to work through for a proper diagnosis or re-assurance. If you get to the end and all the boxes are ticked, I'd say your cooling system was probably o.k. If you go on a long journey ignorant of what's happening or not and something bad happens, then it's to late to go back.

Well that's something. Diagnostics can read the fitted ECU header to get type and firmware information, the original ECU is fairly easy to put back for a scan test and unless it's completely faulty (car won't start) you can get that read and compare the two? I bet that ECU is o.k, but once they order it up from V.W, open the sealed bag and try it, they have to charge you for it.

You say your radiator isn't overheating but you don't know if it's lost efficiency? Doing what I suggested will tell you that. You can wait until the hottest summer day, idle the car after a drive and if the fans don't go off for a very long time, you will have an answer - poor cooling system efficiency?

Every CEL on event is backed up in the fault log. The problem is they didn't know how to analyse the fault code and determine what was causing it! This can happen with intermittent problems, but knowing the fault codes they should have gone further and used their diagnostics to assess the performance of the cooling system. Even if they were working blind, they could have taken a gamble and checked thermistor temperature sensors and wiring.

If you don't want to do any further investigation or checks, that's another strategy which may eventually lead to a more obvious fault. You could be relying on V.W engine self protection after a CEL comes on to warn you or it stops your engine to protect itself.

You seem to have convinced yourself that 20C below is cooling system related? But there are other more important temperature dependent parts to an Efi engine - e.g MAF sensor. When you put your trust in others and can't do anything yourself, you have no choice but to rely on them. Now you've moved, you can't keep going back to complain about the same fault so you either put up with it and wait for something more obvious to happen, or start the journey again with a new local dealer?

Your going a step further ahead of yourself. Fault logs were checked over and over every time the light came on.
The cooling system wasn't an issue 2 years ago. This is a different issue, if its an issue at all. It heats and the air conditioning is working fine. I smelt a "Hot" rubber smell. The type you get when it overheats without the over heating sign. Maybe it was nothing.I was just wondering why the fans were not on when the car was running but yet after it was turned on they kicked on for a few minutes. TO be determined. I will keep a more watchful eye on the temp gauge next time I drive it.
The mechanics that worked on the "Check engine" tried everything that the people at VW told them to do and look into with no results or hints of what was causing it. They had the car for about a month and couldn't find where the problem was coming from. AS I said they replaced everything they thought could had caused this issue.

 

[STIPER2]

Your going a step further ahead of yourself. Fault logs were checked over and over every time the light came on.
The cooling system wasn't an issue 2 years ago. This is a different issue, if its an issue at all. It heats and the air conditioning is working fine. I smelt a "Hot" rubber smell. The type you get when it overheats without the over heating sign. Maybe it was nothing.I was just wondering why the fans were not on when the car was running but yet after it was turned on they kicked on for a few minutes. TO be determined. I will keep a more watchful eye on the temp gauge next time I drive it.
The mechanics that worked on the "Check engine" tried everything that the people at VW told them to do and look into with no results or hints of what was causing it. They had the car for about a month and couldn't find where the problem was coming from. AS I said they replaced everything they thought could had caused this issue.

I will most likely run it into a VW dealer to have them check out the coolant/radiator system to make sure its up to snuff before putting it on any road trip.! The car is in great condition. I am 3rd owner with 2nd owner only had it less than a year and left the country and sold it to me. Thanks for your input! I am many things but a mechanic I'm not.