BMW Z4 Cold Start Mystery: PTC Heater or Something More?

Hey! I had a similar problem with my 2005 BMW Z3 last winter. The symptoms were exactly like yours, super slow warm-up, rough cold starts, and my fuel economy took a hit. The PTC heater was indeed the culprit. I got it diagnosed at the garage, and they found that the auxiliary heater element was completely burned out. It's actually a serious issue because it affects both engine performance and cabin heating. When I brought my car in, they had to replace the entire PTC heater unit and some related wiring that got damaged. They also found that the issue had started affecting the engine control module readings. The repair wasn't quick, took them about two days to get everything sorted. My advice would be to get it checked soon before it potentially causes more problems with other components. This isn't something you want to leave unattended, especially during cold weather. Hope this helps with your decision!

Thanks for sharing your experience! That's really helpful since I'm dealing with the exact same symptoms. Quick question, do you remember roughly how much you ended up paying for the whole repair? Also, has everything been running smoothly since then, or have you noticed any other issues pop up? I'm trying to budget for this and want to make sure I fix it right the first time around.

Hey again! Just wanted to follow up, since I got the PTC heater fixed, my Z3 has been running like a dream! The whole repair set me back about 350 € for the electric auxiliary heater replacement, which honestly wasn't as bad as I'd feared. The mechanic did a great job, and I haven't had a single issue since then. The car warms up properly now, those rough cold starts are completely gone, and my fuel consumption is back to normal. It's such a relief not having to wait forever for the engine to warm up anymore! Seriously, it was money well spent. If you're worried about costs, I'd say this is pretty standard for this type of repair, and it's definitely worth getting it sorted before it causes any other problems. Trust me, you'll notice the difference right away once it's fixed.

Thanks so much for all the details! You actually convinced me to bite the bullet and get it fixed. Just got back from the mechanic today, and I'm so glad I went! My experience was quite different from my last mechanic visit. This new guy really knew his stuff, spotted the issue right away and fixed it much quicker than I expected. The whole thing cost me about 400 €, slightly more than what you paid, but they also replaced some worn wiring while they were at it. Money well spent if you ask me. Started her up this morning and wow, what a difference! No more endless waiting for warm-up, and she's running smooth as butter now. Really appreciate you sharing your experience. It definitely helped me make the right call instead of putting it off and potentially causing more damage. Thanks again for the solid advice!