Sporadic coolant warning light

lord_farquaad · Post by **lord_farquaad** » Sun Feb 05, 2023 4:01 pm

Hi,

I have a sporadic coolant light that comes on and off all the time. Can come on at any time and goes off shortly after. That said it doesn't come on at all when stationary and left running for any amount of time.

I have two error codes though I'm not sure when they 'arrived' and might have nothing to do with it"

27C3 - thermal oil level sensor
279D - engine fan activation

I don't seem to be losing any coolant. . . I've never topped it up and the float bounces back.

Fan does activate when needed. And the engine never seems to get hot, or beyond the half way mark. Nothing different in how it runs also.

2003 3.0 Z4 automatic.

Any assistance would be very welcome.

enuff_zed · Post by **enuff_zed** » Sun Feb 05, 2023 4:24 pm

The float is a visual aid only. It covers the top two thirds of the tank. There is a lower magnetic float at the bottom third of the tank which operates a sensor set into the bottom of the tank. It is most likely an issue with that sensor. Easy to change, twist and pull out. It is in a dry tube so you won’t lose any fluid

bigwinn · Post by **bigwinn** » Sun Feb 05, 2023 4:25 pm

It’s fairly common for the float (which sits in a separate dry chamber) to get sticky

May be worth giving it a tap to free it up or consider a new one if it’s the original as it will fail at some point

lord_farquaad · Post by **lord_farquaad** » Sun Feb 05, 2023 5:02 pm

Cheers, thanks for the help, I've pulled it out. It's a static thing right? Look like the inside of a light bulb??? (Sort of), I've attached an image.

I'll purchase a new one just to make sure. I have the product code from real oem (17137553919).

Wheres the best place to get one, pref next day?

enuff_zed · Post by **enuff_zed** » Sun Feb 05, 2023 5:07 pm

That's the thingummy. I wouldn't worry too much. You have to let the top float get completely dry before that bottom sensor even comes into play, so keep an eye on that while you wait for your new sensor to arrive.
Please also note bigwinn's suggestion. It could also be the actual float sticking inside the tank, which necessitates a tank change.
But a new sensor is the quickest and easiest thing to do first.

lord_farquaad · Post by **lord_farquaad** » Sat Feb 11, 2023 5:33 pm

Well I changed the sensor and also changed the fan belt whilst I was there- it looked cracked etc.

The light on the dashboard is still coming on sporadically still. Damn!

Not sure what to do now,. . .

Interestingly, the sensor I put in had a heat shrink wrap around the sensor element, the I pulled out didn't?

enuff_zed · Post by **enuff_zed** » Sat Feb 11, 2023 6:29 pm

In that case it is likely to be what bigwinn suggested. The actual float that operates that sensor is sticking.
Only answer is a replacement expansion tank.
Easy enough to do, but i guess you just weigh the cost against the annoyance of the light.

lord_farquaad · Post by **lord_farquaad** » Sat Feb 11, 2023 11:19 pm

Cheers, I'll change the tank - I do have one but it's not OEM, it was about £30.

Wheres best to get the coolant from, BMW? And how much do I put in . . .or should I just replenish what I take out - that would be easier.

T_J_G · Post by **T_J_G** » Mon Feb 20, 2023 6:40 pm

lord_farquaad wrote: ↑Sat Feb 11, 2023 11:19 pm Cheers, I'll change the tank - I do have one but it's not OEM, it was about £30.

Wheres best to get the coolant from, BMW? And how much do I put in . . .or should I just replenish what I take out - that would be easier.

I use this https://www.halfords.com/motoring/engin ... 00399.html

but you may have sorted this by now.

lord_farquaad · Post by **lord_farquaad** » Sat Apr 01, 2023 6:54 pm

Update. . . Not fixed!

So I'm going to go through everything I've changed, but I still get the coolant light on.

Changed the expansion tank with OEM one (17117573751)
Changed the Level switch, coolant (under and in the expansion tank 17137553919)
Changed the Thermostat (inbetween expansion tank and the thing it sits in 17111437362)

Changed the Temperature sensor coolant (at the rear of engine- nightmare of a job 13621433076)
Changed the Temperature sensor coolant (at the front of engine 13621433076)
Changed the thermostat housing (front of engine - 11531437040)

I drove and once the Temperature got half way. . . . Coolant light on the dashboard...... not happy.

What else could cause the coolant light to come on?????

Help!!

T_J_G · Post by **T_J_G** » Sat Apr 01, 2023 7:27 pm

Definitely bled properly?

lord_farquaad · Post by **lord_farquaad** » Sun Apr 02, 2023 7:12 pm

T_J_G wrote: ↑Sat Apr 01, 2023 7:27 pm Definitely bled properly?

School boy error! Yeah tried bleeding again and now it's fixed FINALLY!!!!!

if I was to put the overall fix to anything I think it was either the thermostat housing or the thermostat in-between the expansion tank and the thing it sits in, that fixed the sporadic coolant light issue, not the myriad of sensors I changed.

Thanks all for your help

T_J_G · Post by **T_J_G** » Sun Apr 02, 2023 7:15 pm

lord_farquaad wrote: ↑Sun Apr 02, 2023 7:12 pm
T_J_G wrote: ↑Sat Apr 01, 2023 7:27 pm Definitely bled properly?
School boy error! Yeah tried bleeding again and now it's fixed FINALLY!!!!!

if I was to put the overall fix to anything I think it was either the thermostat housing or the thermostat in-between the expansion tank and the thing it sits in, that fixed the sporadic coolant light issue, not the myriad of sensors I changed.

Thanks all for your help

Get in! Just don’t add up how much you’ve spent

But I’m glad it’s all sorted.

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