2014 TDI CNRB - overheating "allegedly"

[TurboABA]

My '14 started running hot according to the cluster temp gauge on a 1.5 hr drive in hot ambient temps (90f), on cruise at 60mph. The guage read a consistent 220-230 for most of the trip.

I tried running the cabin heat on full, turning the A/C off, slowing down, etc. Even sitting at a traffic light at idle would not make the guage go hotter or colder.

Once back home, I ran a scan and not evidence of errors. I then read some values and am now struggling to make sense of them.

Does anyone know which sensor the cluster temp gauge reads off? I'm suspecting a failing sensor because my coolant didn't boil, the fan isn't screaming at all times, and I can clearly tell by touch that the rad outlet is way cooler than the inlet. I also don't have any coolant loss, smoke, smell, or any other form of degradation in terms of performance... Just a temp gauge stressing me out.... No CEL, no buzzer, no engine shutdown, no warning messages, etc.

These are the readings I'm looking at.

Address 01: Engine (7P0 907 401 K)

19:29:15
IDE00025 Coolant temperature 91 °C
IDE00192 Coolant temperature at radiator outlet: actual value 40.3 °C
IDE00194 Coolant temperature at radiator output: specified value 90.0 °C
IDE00196 Engine oil temperature 91.4 °C
IDE00380 Coolant fan 1: activation 81.51 %
IDE03582 Temperature sensor for engine temperature management 143.2 °C
IDE07724 Coolant temperature at engine outlet: calculated 91.1 °C
IDE09976 Coolant fan 1: activation 81.68 %

If anyone has any ideas, I'm open to input or suggestions as I smash my face against this issue.

 

[TurboABA]

The saga continues......

Did a bunch of spirited driving last night to see if it would actually overheat.... everything seemed normal.
I then parked and idled while looking at more values, running whatever output tests I thought might cause a CEL or anything useful, etc.
The gauge actually maxxed out at one point for a brief second, but then returned to the normal 220-230F range that it seems to like as the new "norm" now. I was really shocked to see that there way no flashing warning and\or buzzer even though the gauge went full range briefly. This behavior coupled with the fact that I don't see climbing oil temps or any other overheating signs leads me to suspect a flaky sensor.

More relative info:
- the fan does cycle on/off while idling, but interestingly enough does not stay on constantly even if the gauge reads 220-230f
- the fan will go on as normal if the A/C is turned on

As of right now, I'm leaning towards the G62 Coolant Temp Sender on top of the engine\EGR cooler.
I've thought about a possible water pump failure, but would've expected oil temps and boiling coolant if that was the case.....
Will have to figure out a way to test G62 resistance and perhaps verify system flow to confirm that the water pump is indeed circulating coolant.

 

[rocky raccoon]

An inexpensive laser-assisted remote temperature probe will show the true temps of your various components.

 

[TurboABA]

Agree on temp gun...... after more thinking and reading, I'm starting to lean towards the cylinder head coolant isolation valve since it explains all my symptoms..... if it wouldn't open as required at 90c, then it would still separate the head coolant circuit from the block circuit and thus not transfer any of it's heat to the rad for cooling..... this explains why the temp gauge climbs (probably reads off the sensor on the EGR cooler) while my oil temp and rad outlet temps don't.

I need to figure out if I can run output tests on this valve to validate this theory.... physically getting to it will be a pain since it's under the intake manifold in the vee of the motor, back by the turbo and next to the oil cooler.

 

[TurboABA]

After a lot more reading\studying on this complex system and the ITM involved, I am now speculating that I simply managed to have such low load conditions for an extended period of time and the ITM stepped in to increase cylinder head temps in order to meet\generate the optimal temps required by the smog systems as well as to keep ATF temps in a desirable range.

I have also ordered a boroscope with the hopes that I can get a visual confirmation of the isolation valve working prior to jumping to any more conclusions or to ripping have the engine apart in order to get to it.

 

[TurboABA]

Boroscope came in.... I can barely see parts of the isolation valve under the intake manifold, even when using the borosope.... unless you're an ant, you're not getting to any part of it without removing the intake.

Decided to go for another drive to see if I notice anything else.... upon cold startup (still hot ambient, but vehicle sitting for 24hrs) I noticed that the temp gauge was still reading 220. I have now reverted back to a flaky sensor, so I've ordered the G62 ECT sensor..... will throw that at the problem as my next step.

 

[TurboABA]

Well... after a lot of dealership parts people struggles, I managed to get an Audi dealership to find me the correct part number for the G62 sensor I was suspecting...... however, when I went to pick it up, it was missing one of the o-rings and it was an older revision so I bailed.

That caused me to do some more reading and troubleshooting, so I came home and unplugged the G62 sensor and fired up the egg.....

Address 01: Engine (7P0 907 401 K)

17:03:30
IDE00025 Coolant temperature -40 °C
IDE00192 Coolant temperature at radiator outlet: actual value 32.9 °C
IDE00194 Coolant temperature at radiator output: specified value 90.0 °C
IDE00196 Engine oil temperature 48.8 °C
IDE00380 Coolant fan 1: activation 10.00 %
IDE03582 Temperature sensor for engine temperature management 61.5 °C
IDE04083 Coolant temperatures ECT 1:-40 °C / ECT 2:33 °C
IDE07724 Coolant temperature at engine outlet: calculated 121.0 °C
IDE09976 Coolant fan 1: activation 10.00 %

The cluster temp gauge buried itself instantly and stayed there. No other warnings or anything. Let it idle\warm up a little and shut it down. Plugged the sensor back in. Fired it up again, and temp gauge returned to reading the "normal" overheating state.... ~220f

Address 01: Engine (7P0 907 401 K)

17:20:02
IDE00025 Coolant temperature 68 °C
IDE00192 Coolant temperature at radiator outlet: actual value 34.1 °C
IDE00194 Coolant temperature at radiator output: specified value 90.0 °C
IDE00196 Engine oil temperature 68.6 °C
IDE00380 Coolant fan 1: activation 20.00 %
IDE03582 Temperature sensor for engine temperature management 134.2 °C
IDE07724 Coolant temperature at engine outlet: calculated 68.1 °C
IDE09976 Coolant fan 1: activation 20.00 %

I then noticed that the only reading that is consistently out of wack, seems to be IDE03582.... this caused me to go searching for another temp sensor on the engine. There appears to be one more temp sensor on the front of the motor, just to the right of the water pump, behind an idler pulley. (insert F bombs here)

Digging deeper into SSPs, I found mention of this 3rd sensor. So it appears that the ECM uses some sort of combination of these readings to display what we see on the dumb temp gauge in the cluster. (and probably for other control functions as well)

Engine Coolant Temperature Sensor on Radiator Outlet G83
Engine Coolant Temperature Sender G62
Engine Temperature Control Sensor G694

So now I have to try to figure out the part number for this guy before I can proceed.... (actually hoping that it's the same sensor I had sourced above, but I doubt VAG would make things that easy for me)

 

[TurboABA]

Visuals for anyone who cares.... taken with my boroscope mentioned above.

http://u.pc.cd/JkV7

http://u.pc.cd/3RGctalK

http://u.pc.cd/e6FctalK

 

[TurboABA]

Here are these MOFOs...... I can't seem to find a part number for the G694 in ETKA and neither can any dealership\parts department that I've called.
I will have to pull the pulley off to basically confirm the part number that I suspect it is (basically same as the one on the EGR cooler)
I can only suspect that the actual VAS dealer tool has the ability to actually test each of the sensors resistance to some unlisted or hard to find parameters unless the techs simply start replacing all the sensors until they find the correct one.......

 

[oilhammer]

GFF may have something, but that may only get started if there was an actual DTC to begin with.

The fact that they call one "engine temp CONTROL sensor" leads me to think, like you already thought, the ECU uses that one to keep the engine hot, not merely monitor the static cooling system temp, with the "normal" CTS we usually think of is used for. Some T'regs have one in the radiator lower neck, too, but that is just to make sure the radiator surface temp is hot enough for another passive emissions control (to clean the air in FRONT of the car as you drive). The diesels may not even have that.

 

[TurboABA]

There are no DTCs unless I leave the one that got triggered when I unplugged the sensor on the EGR cooler (which I clearly don't need the DTC to know that it's unplugged LOL)

I will have to result to actually pulling the sensor out of the block and replacing it based on assumptions\process of elimination. Without having the dealer level VAS tool, GFF, oscilloscopes and resistance values, I can't think of a more cost effective way to "find" the root cause.......

No offence to competent industry people such as yourself, but I try to avoid letting the techs around here wearing big red shoes touch my vehicles as much as possible.... even when it becomes a PITA like this..... by the time I pay VW a few hours to "diagnose" my problem, I can just buy and replace all 3 sensors in the "system" and avoid butchers touching my stuff.

 

[oilhammer]

Unfortunately, the absurd complexity often makes anyone that didn't directly design/engineer/program them subject to some headscratching even in professional circumstances. The dealers have tech lines that they can access, though, which often DOES have someone on the other end that has a little better knowledge of what is actually going on.

The Germans tend to think they know better than anyone, and in many cases the diagnostic steps themselves don't always jive with what you would *think* is happening, because you may not be privy to how the system is SUPPOSED to work because they don't necessarily make that information available.

After all these years, I am still not 100% sure what role the lambda sensor plays in the the BEW, as they literally left it out of the official "new" PD TDI product information released to all the dealers. The BKW (T'reg V10 TDI) at least "mentions" the sensor, vaguely, as a way to double check the EGR flow, but... ???

 

[TurboABA]

Double edged sword I guess..... we want technological aids\nannies\features, we have to deal with complexity and F words when trying to diagnose systems.

Oh well... at least I'm not driving a Honduh or Prius

 

[oilhammer]

Oh the Prius has a cooling system that is every bit as complicated, LOL. And the fun thing about those is, all kinds of stuff can fail, and just turn on the one light: the Red Triangle of Death. That could mean anything from low oil pressure because the connecting rods are falling off, or a $3500 catalyst is bad, or the electric water pump for the inverter died and now it cooked the $4000 inverter. Always fun.

 

[TurboABA]

While digging around on rosstech wiki, I noticed this claim..... this could mean that I'm potentially on the right track....

• Freeze Frame data stored at +140*C is generally an indication of a faulty ECT or wiring.

 

[mannytranny]

Thanks for documenting. While it may seem that no one is reading, I've found lots of posts like this over the years associated with a slew of different vehicles that really helps when diagnosing an issue.

Here's to hoping it is a cheap sensor. Sounds like thats the case.

 

[TurboABA]

Super lame update:

I started "working" on it.... it didn't go well.... I didn't have a large enough Torx socket to swivel the V-belt tensioner.... you need a T60 and all my sets only went up to T55.... had to run out to buy one more set!
Got the tensioner locked in the slacked position, removed belt, removed dust cover off the idler pulley only to realize that it is held in place with an XZN bolt (and luckily for me, my XZN bit set is at my parent's place where I typically do my wrenching)...... so epic FAIL.... got about 5 min worth of work accomplished in a whole evening of just pure circus.

At this rate, I might get this sensor replaced this month!

 

[TurboABA]

This sensor continues to just kick my @$$.... got the correct bit, removed the idler and its bracket, got the plug off, but now the damn sensor will not budge.... I'm soaking it in WD40 while raging...... there isn't much room to get a good grip on it with anything and I'm really hoping that I don't have to start pulling intake piping off to get access.

Here are a bunch more pics taken with the boroscope (hence the quality)..... it appears that I've damaged the locking tab on the plug, but at least I guessed correctly at what the part # was, so if I ever manage to get it out, I have the correct replacement.

The rage is strong.....

 

[oilhammer]

Man, you poor guys in the salt belt. Wow that looks awful.

 

[TurboABA]

I just looked to figure out why there's no room.... luckily, it seems that I only need to pull off 4 charge pipes and one charge pressure sensor to get sufficient room!



Rage!

 

[TurboABA]

FML

 

[TurboABA]

If I never have to do that again, it will still be too soon.

 

[TurboABA]

Tornado warnings and storm rolled in.... so I had to tap out for the day....
Managed to get it re-assembled and started it to get some readings. Idled it for 20 min.... at first glance, it appears to be normal. Temp gauge was flat cold on start, and it gradually climbed to 12 o'clock as per normal expectations and stayed there. Readings are more inline now, but I have to still drive it, check for leaks, top off coolant, etc. before I can say it's "fixed". Stay tuned.

Address 01: Engine (7P0 907 401 K)

18:32:27
IDE00025 Coolant temperature 67 °C
IDE00078 Time since engine start 1272 s
IDE00192 Coolant temperature at radiator outlet: actual value 25.8 °C
IDE00194 Coolant temperature at radiator output: specified value 90.0 °C
IDE00196 Engine oil temperature 71.0 °C
IDE00380 Coolant fan 1: activation 20.00 %
IDE03582 Temperature sensor for engine temperature management 75.7 °C
IDE04083 Coolant temperatures ECT 1:67 °C / ECT 2:25 °C
IDE07724 Coolant temperature at engine outlet: calculated 67.2 °C
ENG106231 Ambient temperature 16.5 °C

 

[TurboABA]

Went for a drive......

Log #508978

 

[TurboABA]

Took it to work today.... 18.5mile commute each way on rural and city roads and all seems well..... will probably take it on a long cruise on the weekend and even go grab a load of firewood just to make sure I test it under various conditions before I consider it dealt with.

 

[TurboABA]

Just got back from a "typical use weekend" so I can now confirm that it's fixed and working as it should.

The t-reg got about 200 miles worth of 75mph cruising with just people and cargo mixed with a good 45 min of towing including some stretches of same or greater speeds... No signs of funny stuff or overheating.

 

[Franktank]

Now help me with mine overheating 2014 2.0 tdi Passat reads 220 going up hills. Most of the time runs 190.

where do I start?!?

 

[TurboABA]

Link me to your post were you provide all the details and I'm sure there will be a few that will attempt to help.

 

[Franktank]

2014 VW Passat overheats 20degrees driving up hills

Anyone have this issue where TDI will overheat from 190 to 210 especially up hills? After short cruise the temperature will return to 190. Every now and then it will hover around 210-230. If I give it gas and rev up the engine I can sometimes force the temp back to 190. Sometimes. If not the...

forums.tdiclub.com

 

[Franktank]

Thanks