[jjcannon2]

Hi,


I'm looking to replace the coolant level sensor on my 335i coupe. Does anyone have instructions, or know of any DIY guides, on how to do it?


Thanks

[jjcannon2]

Originally Posted by jjcannon2

Hi,


I'm looking to replace the coolant level sensor on my 335i coupe. Does anyone have instructions, or know of any DIY guides, on how to do it?


Thanks

To be clear, I'm referring to the sensor in the coolant expansion reservoir.

[zzoeller]

yeah I'm very interested as well , mine needs replaced lol it broke

[robc1976]

Originally Posted by zzoeller

yeah I'm very interested as well , mine needs replaced lol it broke

Just s sensor on bottom of tank....a new tank ($80) congress with new sensor....takes 10 minutes to switch out tank..about the same for sensor....here is the sensor.

[Jklad]

Do you need to empty any/all coolant and refill to do this repair?

Thanks

[pwr hungry]

Originally Posted by Jklad

Do you need to empty any/all coolant and refill to do this repair?

Thanks

No, just leave all the coolant in the tank and disconnect the sensor from the tank over your lap. You won't spill a drop. Trust me.

[robc1976]

Originally Posted by pwr hungry

No, just leave all the coolant in the tank and disconnect the sensor from the tank over your lap. You won't spill a drop. Trust me.

Yep, easy as pie

[jjcannon2]

Originally Posted by zzoeller

yeah I'm very interested as well , mine needs replaced lol it broke

Are you having the same "low coolant" error message?

[jjcannon2]

And thanks everyone for their input! Ordered the sensor .. just waiting for it to arrive now.

[jjcannon2]

OK so I installed the sensor and am having a bit of an issue.

I originally decided to chance the coolant sensor because I was receiving recurring "low coolant" warnings despite having an adequate amount of coolant in the expansion reservoir. I would receive the warning (yellow low coolant icon) ~once a day.

Now after replacing the old sensor with this new one, the warnings are happening more frequently!!

For some background: the previous owner changed the water pump, tstat, and radiator recently. Any ideas??! This is driving me insane!

[Miller335]

Are you sure there is only one coolant sensor?

Could there be another one and in reality the coolant is low?

I know expansion tanks work differently than overflow tanks but in the older overflow tank system just because the coolant level in the tank looked good doesn't mean there's a right amount of coolant in the rad/engine (usually the rad cap will control this and is at fault in that case).

How many miles?

[jjcannon2]

To my knowledge this is the only coolant level sensor. There is a coolant temp sensor in the lower rad hose but no other coolant level sensor to my knowledge. Car has 68k

[TheTal0n]

I have a few questions,

Do you need to remove the expansion tank to replace the sensor, or can it be done without disconnecting the small coolant hoses? (worried about spillage or air bubbles getting into system )

Is there any details on how to remove it and re install new one?

Thanks guys!

[jjcannon2]

Originally Posted by TheTal0n

I have a few questions,

Do you need to remove the expansion tank to replace the sensor, or can it be done without disconnecting the small coolant hoses? (worried about spillage or air bubbles getting into system )

Is there any details on how to remove it and re install new one?

Thanks guys!

I removed mine. It's literally two or three bolts to free the reservoir and some hoses that need to be released from the reservoir body. There won't be any fluid leakage since the sensor is fully enclosed. From there you just unclip and twist the sensor and it should come right out.

FYI - I changed my sensor and am continuing to have this issue. Not sure where to go from here.

[TheTal0n]

Originally Posted by jjcannon2

I removed mine. It's literally two or three bolts to free the reservoir and some hoses that need to be released from the reservoir body. There won't be any fluid leakage since the sensor is fully enclosed. From there you just unclip and twist the sensor and it should come right out.

FYI - I changed my sensor and am continuing to have this issue. Not sure where to go from here.

I wonder if i should clear all codes before doing this, even if none show up.

Did you use a OEM sensor?
Did you touch it with your hands on the stick part?(silly question i know.)

[jjcannon2]

Originally Posted by TheTal0n

I wonder if i should clear all codes before doing this, even if none show up.

Did you use a OEM sensor?
Did you touch it with your hands on the stick part?(silly question i know.)

I used an OEM sensor and didn't touch the sensor at all. You'll know right away if you installed it incorrectly if the coolant low error comes up immediately when you turn on the car (Rather than after some driving)

[frederickhsu]

Originally Posted by jjcannon2

I used an OEM sensor and didn't touch the sensor at all. You'll know right away if you installed it incorrectly if the coolant low error comes up immediately when you turn on the car (Rather than after some driving)

Sorry to revive an old post.. but what happened ? Did you fix it ?

[pb335i]

I’m running into the same issue as well. How did you fix the issue? I changed my water pump and thermostat due to the water pump leaking again and decided to also change my tank while it was empty because the bobber was broken. The tank was aftermarket and now I’m getting a low coolant light and decided to swap the sensor with my OEM one that was working initially and now neither solutions have been successful and I still keep getting the yellow low coolant light. Let me know how this issue was resolved thanks!!

[feuer]

Originally Posted by pb335i

I’m running into the same issue as well. How did you fix the issue? I changed my water pump and thermostat due to the water pump leaking again and decided to also change my tank while it was empty because the bobber was broken. The tank was aftermarket and now I’m getting a low coolant light and decided to swap the sensor with my OEM one that was working initially and now neither solutions have been successful and I still keep getting the yellow low coolant light. Let me know how this issue was resolved thanks!!

Issue is with the tank.

[pb335i]

Originally Posted by feuer

Issue is with the tank.

Thanks for the response, curious to know the reasoning behind the issue being the tank?

[feuer]

Originally Posted by pb335i

Thanks for the response, curious to know the reasoning behind the issue being the tank?

I have explained this in another thread. The tank got two floats. One with the plastic bar that pops up when you open the cap, the other with magnet that work the level sensor (this is why coolant doesn't run out when you remove the sensor). The magnet is stuck on the bottom or isn't present at all. Maybe if you remove tank flip it, shake it, tap on it....will decide to start working. But I usually replace them. Sometimes people damage them by sticking a funnel into the tank for fill up.

[pb335i]

Originally Posted by feuer

I have explained this in another thread. The tank got two floats. One with the plastic bar that pops up when you open the cap, the other with magnet that work the level sensor (this is why coolant doesn't run out when you remove the sensor). The magnet is stuck on the bottom or isn't present at all. Maybe if you remove tank flip it, shake it, tap on it....will decide to start working. But I usually replace them. Sometimes people damage them by sticking a funnel into the tank for fill up.

Thanks again for the clarification, this issue was making me go insane with all the coolant problems I've been having. Had a leak and replaced my water pump and thermostat then drove it for a day and the coolant hose flange cracked. Had a nice lucky day for problems. Thanks for the response I'm going to try and find that thread you mentioned to do more reading. Any suggestions on potentially trying to fix the issue or will I have to replace the tank again.