Had 4 of these fail all within 3k miles. All had the same failure mode of leaking at the electrical connector. The last one failed immediately upon installation. FCP's lifetime warranty is fantastic but I think I'm gonna get a Mahle now.

I installed one of these about two years ago, on 01/19/23, and after a couple of months, the thermosensor integrated into the thermostat body started malfunctioning. A month ago, it got stuck in a pre-opened position, leading to overheating. Not recommended.

Bonafide BMW parts are the best parts.

I need to have a quick word with whoever is installing the thermostat sensor oring without any f***ing lubericant lmao. So far two of these have developed leaks within 6-10 months all from the connector area. I found a way to remediate this issue by removing the sensor carefully. You have to pry up on a flap and carefully twist the connector counter clockwise and pull out carefully with pliers. Helps to spray silicone lubricant around this area to make sliding out easier. now clean out the hole of the thermostat and inspect the oring. If its torn due to improper installation from the monster factory line workers as mine was, replace it. I applied rtv from victor reinz and reinstalled it. So far its been good for 1k miles. Hopefully this will work in the long run. If not, im going with the genuine one......

Replace my WP almost a year ago and i have not had not 1 leak or coolant loss. I drive my car pretty hard and no more problems, again knock on wood. Im sure now that i said something my cooling system will decide to act up. But great part at a great price.

Installed 6 months ago. The thermostat has a small leak at the connector. Will be replacing again.

Everybody says this is the best brand thermostat for the E46 and if it fails, it gets stuck open, so no harm. Well, mine failed in about a year after installing it and it FAILED CLOSED, causing the car to overheat. Thankfully FCP Euro gives a lifetime warranty, so I got my money back and switched to Mahle. Let's hope the new one will last more!

I've been using Whaler thermostats since 2020 to replace the Mahle version that I had originally which only lasted for a couple years as it got stuck open. This is the third Whaler thermostat that I installed and as soon as I fired up the engine the coolant temperature gauge would not sit dead center even after letting it idle for about 15 minutes and then going for a 30 minute drive. What's crazy is that the last two only lasted a year whereas this one just stayed in the open position right out of the box. I even ran the engine without the heater connector and it still was stuck open. I'm going to revert back to the Mahle version again and if that's a dud, like the one I used about 4 years ago, too I'll have to buy the OEM BMW one. It's crazy that manufactures can't even make something as simple as a thermostat with decent quality.

Bought for 2006 BMW X5 3.0i. Temp gauge was running cooler than normal. Replaced thermostat and lower radiator hose, bled it once, took it for a drive.. Still was cooler than normal. Then I topped off the coolant again, took it for a drive, and it was fixed. Has been running at normal temp now (was installed in March 2024).

This unit lasted the car about 4 yrs with below average mileage driving at normal pacing, not aggressive. Replacing with Genuine BMW unit now. The connector plastic area in the center of the thermostat exterior started to leak coolant and shorted out the connection giving rise to "service engine soon" light.