Coolant leak without warning

[FAM]

Hi everyone,
I had oil changed on my 2006 X5 E53 and after the oil change, I noticed a leak. I went back to the mechanic but he tried to convince me that it's the power steering leaking. I came home and put clear plastic under the truck and next morning I saw a puddle of yellow water like liquid, went back to the mechanic with a sample of the liquid and then he said it's the coolant leaking and it would require the hose and sensor replacement.

My question is, why and how can a simple oil change result in coolant leaking? Why do I need to change the sensors? Is there an easy fix for it. Would it really be the coolant? it's my first BMW and I'm pretty anxious about this unforseen problem.

I'd appreciate your help and advice.
Fam

[Nanniepoo]

It's probably just a coincidence. I recently had to get my AC recharged after doing coolant work, and thought I damaged something, but the mechanic couldn't find anything wrong and just recharged it.

Just from my recent experience, you can't swap the sensor over. I'm not familiar with the E53, but on the E70 the sensor was located on the hose. The o-ring was compromised. Maybe with a little grunt work you can find a replacement o-ring but the sensor was fairly cheap, so I just bought a new sensor to pop in.

Normal BMW coolant is blue, so the yellow is suspect but if it was sampled as coolant, I would think it was coolant. And sounds like he diagnosed where the leak is coming from too.

[andrewwynn]

I would be surprised if it's anything different on the E70 or any other BMW they probably use the same sensor and o-ring. When mine leaked I wrapped some Teflon tape around it as a "temporary" solution but after buying some o-rings I never bothered to replace as the Teflon has been holding for over half a year now maybe nine months