Fault code 16500 (G62) - Engine Coolant Temp Sensor - Only when cold

[swimr612]

I have a 2002.5 GLI (VR6-24v). Every winter, first thing upon starting up on a cold day (less than about 40 degrees F) my coolant temp light goes on (flashing). I've read the following code, which appears to be related to the dash light:

16500 - Engine Coolant Temp. Sensor (G62): Implausible Signal
P0116 - 35-10 - - - Intermittent

If I drive around for just a few minutes and cycle my ignition, it won't come back -- not even if I turn off the car completely and start it up a few hours later. It also never occurs during the summer.

This only happens on cold days, first thing in the morning, which leads me to believe it has something to do with the coolant temperature being too cold... I run with Genuine VW coolant (pink) mixed 50/50 with distilled water. I even added a little more coolant (to make it about 60/40) just in case, but to no avail.

I've also replaced my temp sensor (now have the green one) and reset the code via VAG-COM, but it keeps coming back.

Anyone else have a similar issue, or any ideas on how to solve this??

[vwemporium]

auto-scan first maybe do some reading, maybe a search?

[swimr612]

I posted the results of my autoscan, and I've searched far and wide across many websites including throughout these forums. There have really been no indications of anything throughout these forums except for a shorted temp sensor, or low coolant level. Also, no explicit mention of this *only* happening in cold weather.

Since I've replaced the temp sensor, the coolant level is fine, and my cold-weather-only symptoms are different from everything I've read so far, I'm not quite sure what you're implying I should be doing that I haven't already...

If you or anyone else has a solution, I would love to hear it.

[vwemporium]

Post it here.

Lets see it.

Please provide full name and lic # of your cable so I may verify with Ross-Tech and I will personally help you.

Send this to the IM or email vwemporium@aol.com

Best,
Jack

[swimr612]

VCDS Version: Release 805.1
Data version: 20080823

Chassis Type: 9M - VW Golf/Jetta IV
Scan: 01 02 03 08 15 16 17 19 22 29 35 36 37 39 46 47 55 56 57 75
76

Address 01: Engine Labels: None
Part No: 022 906 032 BM
Component: MOTRONIC ME7.1.1G 0004
Coding: 00032
Shop #: WSC 00066
<VIN removed>

1 Fault Found:
16500 - Engine Coolant Temp. Sensor (G62): Implausible Signal
P0116 - 35-10 - - - Intermittent
Readiness: 0000 0000

<No other faults throughout autoscan.>

[vwemporium]

OK

I verified your human race papers.

Have you checked the following?

Fans operation + control module + thermo switch @ time/temp of turn on.
Water pump mechanical and electric.
Thermostat operation and correct part # temp rating.
Expansion tank and or cap seal.
O-ring for water flanges and behind timing cover between block. (BDF )
Does the system maintain a seal cold?
Cross contamination?
Leak at seem of heater core or radiator.
Leaks?
Ground connections
Supply voltage

Wiring is correct in sensor housing in comparison to WD.

Send me a log of coolant temp during cold warm up cycle, and drive car also log, until DTC appears, to determine if possible sensor or harness issue.
For 01 and 17 for the temp Gage.
No short cuts because I don't trust your judgment being you haven't fixed already.
Complete auto-scan.
No wining the dog ate it.

Show your home work

Best,
Jack

[SilverSquirrel]

Any resolution?
Im having intermittent G62 implausible signal issues as well. My mechanic has vag-com license, and thought we had a fault at the cluster harness. I replaced the G62 and G83 sensors. The gauge stops working, a few days after re-set of the fault, and after a few days driving, will throw a cel.
My car is an 06 A3 w/3.2 VR6 BUB.

[vwemporium]

Again post an auto-scan or start your own thread with an auto-scan.

[SilverSquirrel]

thanks, will do.
I have the printout from my mechanic, and the car goes back to him next week for more scanning and diagnosing. I will post a new thread If we have no luck. Its a bad connection somewhere, we think. Just have to find it. its very intermittent.

[swimr612]

It appears to be gone now after I performed a full coolant flush this past week (for other reasons). Since I really didn't touch anything other than the lower radiator hose connection, I can only guess that there was something wrong with the coolant mixture that was in the system before. (Possibly topped off with non-G12 or something?)

Doesn't sound like this would be much help to you though. Sorry...

[vwemporium]

Sure you can have electrolyte coolant.

Just proves the coolant should not be rated as lifetime.

But then what is the definition of lifetime by a State or Federal agency.

[SilverSquirrel]

Quote, originally posted by vwemporium »

But then what is the definition of lifetime by a State or Federal agency.

That depend on if you owe them, or if they owe you!