Blue Lights on Gauges in a 03 Tdi
- #2
I had the coolant idiot light blinking on my car and it turned out to be the coolant temp sensor. I think it's a similar part on the PD's but don't quote me on that. IMO, that's where I'd look.
- #5
I recently had the same problem. I checked the coolant level in the reservoir, which was fine. Then I talked to JASONTDI and he suggested that it could be poor contact in the connector to the sensor in the coolant bottle. Cleaning the connections which looked fine, did not help.
Then still suspecting the coolant level sensor, I took a small piece of 3M nylon abrasive pad in a forceps and polished the sensor bars that are visible thru the filler of the coolant bottle.
This fixed the problem. I think there was some invisible surface film on these bars that did not allow the sensor to read the correct value.
- #6
saa004 said:
Sorry, I'm not sure what you meant by IMO. And where is the temp sensor located. I don't have a maintenance manual.
thanks
IMO is shorthand for In My Opinion. The coolant temperature sensor is located, at least on my car, on the driver's side of the engine, facing back toward the firewall of the car. You'll see a junction of coolant hoses there, and then something toward the back with an electrical connection going to it. That should be the coolant temp sensor. If you do a search through here, I'm pretty sure there's a procedure somewhere on how to change it. Like I said, that's what I did, and it fixed my problem.
- #8
Mine used to do it whenever the temp was below freezing, but has recently been doing it as high as 46 degrees (via scangauge).
I've been frustrated by the typical responses... There's plenty of coolant there. The contacts are strong. It's a good mixture. And my temp gauge is good (again, scangauge).
Re-cycling the ignition once the coolant is above 60 degrees is the easy fix for the light, but it confuses the hell out of the scangauge, so I've just been leaving it alone to blink recently.
I am excited to try the scouring pad... It would be nice to have a real solution to this little issue.
- #9
The coolant temperature sensor actually sends out two signals. One to the ECM, which is what I believe your scanguage is reading, the other actually goes to the temp guage or temp light, depending on particular model. My dash light would blick also, yet the car would run fine. Since I replaced the coolant temperature sensor, the light has not blinked once since then. I would take a closer look at the coolant temp sensor. Just my opinion, take it for what it's worth.
- #10
I will (thanks for the extra info), provided scouring the coolant probes doesn't work.
We'll know in a few days...
- #11
3 mornings below the dreaded 46 degree threshold, and so far, no light.
- #12
Did this work?
I am bringing this thread back to life because I am curious if my scouring fix worked for anyone else.
Has anyone tried this with success or failure?
- #14
rez311 said:
__. Every autumn for the past three, at about the first cold snap, I'd start my car in the morning and the light would flash. Same as OP, if I drove it a mile, switched it off, and then started it again, the light would be gone and would stay off until the next morning.
__. The level in the bottle would always be normal (actually, just closer to full). I'd add 4 oz. of distilled water and the light would go out ... until the next autumn. I tried the "cleaning the contacts thing" -- didn't work (but I was wussy about it because I didn't want to overstress the contact prongs so maybe I just needed to scour harder).
__. As a result of this, my bottle has "ratcheted" up to very close to the MAX full line. But it still did it last autumn. And 4 oz. of distilled water fixed it, again.
- #15
I have the same exact issue with two same year, make and model PD TDI's. One silver, one dk blue. One stick, one auto.
On a cold morning light goes on, and you can drive just a block or so - turn the car off then back on - and the light will go off and remain off.
The indicator is positively correlated to the temperature. Colder days cause an issue, warmer days do not. And it is perfectly consistent, on the coldest days you will always find the light goes on.
With one vehicle I added 1 cup of water even though it appeared that the coolant level was perfect. The light went out and never came back on. Problem solved.
With the other car I have done nothing yet and the light still comes on when cold out. It does seem the dividing line for triggering it is just below freezing, but low twenties and below will always find it triggered.
Interestingly on one of the vehicles the problem began the day after Jasontdi had installed an inline 1500w coolant heater. There were no leaks and the coolant was full, but I had initially thought it was related. This occurred at the start of it's third winter. The second vehicle did not have any issue until this year, its fourth winter (This is also just after Jas, did the 100k timing service on it. 
) . Here is my original post on the issue: http://forums.tdiclub.com/showthread.php?t=195846&highlight=coolant
My guess is that adding even just a few drops of water to the reservoir finds just enough slightly less mucked up wire to complete the circuit and send the full signal out to the light. There's probably a better cleaning aid for the sensor strip than steel wool though ...
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- #17
SuburbanTDI said:
Until that part of the probe gets mucked up. Your guess is right, in that you've just put coolant where it had never been, so when the signal is sent... the car sees it.
I used one of those 4 fingered "pick-up tools" and a 1" x 0.5" cutting of new scouring pad from a sponge. I didn't press super hard, but I took some time and was very thourough in cleaning off both probes.
And FWIW... I've not replaced my coolant sensor. It sends good info to the scangauge, and I've seen nothing to lead me to believe that the other, digital part of the sensor (the part that sends the overheat signal) is malfunctioning.
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- #18
Variant TDI said:
__. Yupp, and so many of them are bad right out of the box, changing one that works is *asking* for a crap shoot. Leave it alone if it's OK.
- #22
Stock coolant (IIRC) is G12, any of the reputable online places will know. (Although if you're just adding a trivial amount, I just put in distilled water.)
Option for cleaning the coolant probes: Toothbrush. Preferably new.
At 115k miles, my stock black coolant temp sensor started getting quirky. 2 mornings ago, it thought it was -40 degrees out, and kicked me into a high idle. Replaced it with a green one, and it's all good again.
Source: https://forums.tdiclub.com/index.php?threads/temperature-light-blinks.238744/
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