Blinking red temp light, but not overheating?

mrchaotica · Oct 20, 2010

Recently, my Beetle's temperature blinking red high temperature light (remember: Beetles don't have actual temp gauges) has gone off a few times. It's tended to happen while I'm stopped at a red light, facing uphill. After pulling over and shutting the car off for a minute or two (not long enough for it to cool down if it were genuinely overheating), I can turn the car back on and continue driving without the light coming back on. Even more weirdly, my Scangauge indicates that the water temperature is in the normal ~180 degree F range even while the light is blinking (and the buzzer is buzzing) at me.

I have no idea what's wrong (except that I'm pretty sure the car isn't actually overheating). Anybody have a guess?

fase2000TDI · Oct 20, 2010

mrchaotica said:
Recently, my Beetle's temperature blinking red high temperature light (remember: Beetles don't have actual temp gauges) has gone off a few times. It's tended to happen while I'm stopped at a red light, facing uphill. After pulling over and shutting the car off for a minute or two (not long enough for it to cool down if it were genuinely overheating), I can turn the car back on and continue driving without the light coming back on. Even more weirdly, my Scangauge indicates that the water temperature is in the normal ~180 degree F range even while the light is blinking (and the buzzer is buzzing) at me.

I have no idea what's wrong (except that I'm pretty sure the car isn't actually overheating). Anybody have a guess?

Coolant level too low?

Yblocker · Oct 20, 2010

Have you checked the coolant level in the reservoir? There is a low coolant sensor in there that when closed, will trigger the light. Try adding some correct 50/50 mix coolant/water and see if that fixes it. The coolant doesn't have to be very low for this to happen, thus your normal temperature.

Ol'Rattler · Oct 20, 2010

Bad sender for the temp sender. Remember the idiot light temp sensor and the ECU temp sensor are 2 different sensors.
Low coolant level or defective coolant level sensor.

04SlvrJetta · Oct 21, 2010

I had this problem last winter on my '04 Jetta. It would do this on cold mornings but not on subsequent starts through the day. Try locating the coolant level senser (looks like 2 metal probes about 1/16" dia) in the overflow tank and clean it with an old toothbrush. They get some buildup on them and start to show like the coolant is low.

TDICADDGUY · Oct 21, 2010

On a New Beetle, blinking red means low coolant. Steady red means overheating. Its in the manual.

If your coolant level is normal, then I'd say its the sensor or connector on the reservoir.

fruitcakesa · Oct 22, 2010

My Jetta has been doing this for the last 100k miles.
I cleaned the coolant probes to no avail but have not replaced the reservoir. Only happens below 50* and will go out and stay off when I shut down and restart.

procupine14 · Oct 22, 2010

Yeah I was going to say...your coolant level sensor is faulty or your coolant is low...when the car overheats its a solid red on Beetles. The blinking is low coolant or indication of a faulty coolant level sensor.

mlemorie · Oct 22, 2010

There is an updated reservoir too if yours is still the factory one. The new one no longer has the extra shielding around the sender probes, or any of the extra baffling inside the tank.

bob6715 · Jul 22, 2015

blinking red temp light

7-20-2015
but very first check that the heater core is not leaking in the car mostly on the passenger side these carpets will hold a lot of water, feel the carpet, if saturated heater is leaking (very common), just disconnect the heater hoses and reconnect one in a loop back to the engine, refill and drive, if no more blinking light then heater core needs to be replaced.

SaxmanKana · Jun 25, 2019

Thanks guys, very helpful!

Blinking red temp light, but not overheating?

mrchaotica

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fase2000TDI

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Yblocker

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Ol'Rattler

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04SlvrJetta

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TDICADDGUY

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fruitcakesa

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procupine14

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mlemorie

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bob6715

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SaxmanKana

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