Aftermarket coolant temperature sensor warning!

[witchcraftz]

My coolant temp sensor was defective so I bought one from ECS tuning, thought it was OEM but turns out it wasn't.

I took the car for a test run after installing the sensor and everything looked good.

I was driving today (1 day later) and everything was good for about 30 km. Around that time I had to do a quick acceleration to merge onto a busy highway.

My coolant temperature suddenly started going all over the place, dropping to zero and then coming back to mid, then dropping again until it went back to zero and stayed there.

Needless to say I took my first exit and stopped in a parking lot. Once stopped I opened the hood and I could see that the coolant temp sensor had completely come out of it's clip and all my coolant was gone in steam.

In the parking lot I pulled the airbox out and then reinstalled the sensor (some lightly burned fingers happened, caution your engine gets hot), then just to be sure it was secure I gave it a bit of tug, it popped right back out. I did this a dozen times trying different angles to the sensor until I finally had the clip jump out of my hands and get lost.

Luckily I was a 20 minute walk from a VW dealership and in a Canadian tire parking lot.

I walked to VW with my sensor in hand. At VW I compared my sensor and the one they had, there is a minute, but noticeable, and VERY critical difference!

The OEM sensor has a "flat" metal edge, the Aftermarket is "rounded". This round edge means that with a bit of pressure the sensor pushes the clip up and pops out!

I got real lucky with my problem, I was close to a dealership to buy the OEM part and get coolant. I also happened to still have a couple of tools in the car.

Here is a picture of the aftermarket so you can see. Make sure you get the OEM one!
The red dashed line is where the OEM sits, much flatter than the aftermarket one.

[kujiwara]

Re: Aftermarket coolant temperature sensor warning!

Thanks for sharing the info! You should talk to ecstuning about how they didn't send you OEM part and it failed, hopefully you'll get a refund.

[witchcraftz]

Re: Aftermarket coolant temperature sensor warning!

Some non-OEM sensors I saw on Google have a more flat edge like the OEM but you can't tell the difference without having the OEM and aftermarket side by side.

Just imagine how bad this could be if you don't notice your temperature gauge going all over the place before dropping to zero! You would think your engine is running strangely cold when if fact it is overheating because you have no coolant, it could easily destroy your engine.

[MechEngg]

Re: Aftermarket coolant temperature sensor warning!

You would also get a low coolant light on the dash with an audible warning to stop the engine immediately.

[BaggedGLI]

Re: Aftermarket coolant temperature sensor warning!

This is why we only used genuine sensors at CAW. From poor manufacturing to faulty new sensors, it isn't worth it for the few bucks difference in price.

[witchcraftz]

Re: Aftermarket coolant temperature sensor warning!

You would also get a low coolant light on the dash with an audible warning to stop the engine immediately.

I would have expected that too, but I didn't get the warning until after I parked.

My hypothesis is that the remaining coolant was turned to vapour due to the lack of pressure, and that vapour kept the sensor "wet" enough for it not to know the coolant was gone.

[Benjamin]

Re: Aftermarket coolant temperature sensor warning!

If coolant turns to vapor due to being so low, your bubble would have empty several liters before that happens. Just how the bubble and coolant flow works with vw and the height would have the bubble empty well before your block was low enough for steam.

[witchcraftz]

Re: Aftermarket coolant temperature sensor warning!

If coolant turns to vapor due to being so low, your bubble would have empty several liters before that happens. Just how the bubble and coolant flow works with vw and the height would have the bubble empty well before your block was low enough for steam.

Well I had to refill my coolant after it all came out, it took 2L of coolant and 2L of distilled water to refill it. So yes, several (4 out of 6) liters did empty out. As for coolant turning to vapour I can attest to that as there was coolant steaming coming out of the coolant sensor holder.

I hold to my hypothesis.

Perhaps there is a misunderstanding on the coolant temp sensor I am referring to?

[Benjamin]

Re: Aftermarket coolant temperature sensor warning!

I trust that there was steam, I am more trying to point out something is wrong with your low coolant warning system.

If you have an old spare bubble hook the sensor up to it only and see if your dash lights up and screams at you. If the dash does nothing with an empty bubble you have wiring/cluster issues of some sort.

Mine screams at me at a half liter low I am pretty sure. Just trying point this out so your car won't run low on coolant and screw your engine if something is wrong.

[witchcraftz]

Re: Aftermarket coolant temperature sensor warning!

Ah, got it.

The low coolant light did come on after I pulled over in the parking lot.
It also remained on until I had enough coolant back in there, so it seems to be working properly, I don't have a spare coolant bubble to test a dry run though.