This faulty headlight switch circuit board is causing BMW E46s to catch fire.

      The BMW E46, part of the 3 Series from the 2000s, offers an excellent driving experience and has a robust aftermarket, making it accessible for purchase and modification with relatively limited resources. These cars hold significant cultural value, and their preservation is essential, which includes preventing issues such as spontaneous combustion of the circuit boards behind their headlight switches. Known as "LCM fires," this topic has been a point of discussion on BMW forums and Facebook groups for years, but someone has now taken the initiative to explain how these fires occur and, importantly, how to avoid them.

      Currently, most issues encountered by E46 owners are typical problems found in older cars, such as oil leaks and deteriorating bushings. However, there are a few specific concerns that frequently arise in owner communities, including the failure of plastic cooling components that lead to overheating, cracks near the rear subframe mounts that compromise chassis integrity, and the headlight switch potentially igniting, even when the car is off.

      The real concern is not the headlight switch itself but the horizontal circuit board located behind it, known as the Light Control Module (LCM). In the left-hand-drive E46 models most are accustomed to, it resides to the left of the steering wheel, just above the driver’s knee. Although there are various light switch types in these vehicles (some with an automatic setting and others with a fog light button), they all share similar fundamental construction.

      While I haven't determined a definitive number of E46s that have suffered from LCM fires or whether specific trim levels are more at risk, after watching Tyler O’Leary's video on his YouTube channel, O’LearysGenuineBMW, it seems no E46 variant—including hardtop or convertible, with or without sunroof, and regardless of automatic headlight mode—is entirely exempt from this issue. This video is essential for anyone who owns an E46, is considering purchasing one, or has a general interest in the model.

      There is some speculation among owners online regarding possible causes of these fires, like clogged sunroof drains or leaving the lights in automatic mode. However, since E46s are generally older models, even those without sunroofs might still allow moisture to enter the cabin through worn seals.

      As O’Leary explains, these LCM circuit boards are exposed to a constant voltage (which allows the lights to function even without the ignition key). When moisture reaches the boards, it leads to corrosion, which then increases electrical resistance. This resistance generates heat, and under certain conditions, heat can ignite a fire.

      While there are various kinds of BMW E46 light switches, the LCM housings have a similar appearance; they resemble the ribbed plastic box behind the light switch. Interestingly, I haven't encountered a report of an LCM fire occurring while a vehicle was in motion. Although I'm unsure what this signifies, I will certainly begin checking the LCM in my wife’s 2003 BMW 330ci regularly.

      For E46 owners, ensuring your sunroof drains are clear and that your cabin weather seals are intact is the first step in preventing LCM fires. Given the widespread nature of this issue, it’s wise to visually inspect the module itself. O’Leary demonstrates a straightforward inspection process—the trickiest part may be carefully removing the trim around the light switch without damaging it.

      Once the module is detached, you may find either a clean one (great) or a dirty one (unfortunate, yet preferable to discovering problems when your dashboard is in ruins). After accessing the circuit board, you have a few options; you could attempt to seal it with a moisture-proof product, but proceed cautiously and conduct thorough research to avoid damaging components with incompatible substances. Alternatively, silicone sealant can be applied around the outer edges of the switch housing, but again, ensure that you're not creating unintended contact between materials.

      A quick search in an E46 owner’s group on Facebook yields numerous threads discussing LCM fires.

      You can entirely replace your LCM by checking part numbers on RealOEM, though they aren't inexpensive. For example, FCP Euro charges nearly $500 for the headlight switch in my wife’s car. Used options are available on eBay and at salvage yards for a significantly lower price, though purchasing used carries the risk of repeating the problem unless the seller has inspected and verified the LCM.

      If you find this situation concerning but lack the motivation to investigate further, you might consider disconnecting the battery, which would cut power to the LCM and other systems. However, this is not a long-term solution unless you're planning to store your BMW for some reason.

      Alternatively, if you genuinely dislike your E46, you could wash the LCM in your sink, reinstall it, park far from your house, and prepare to file an insurance claim—just kidding!

      On a serious note, there's another aspect to keep in mind concerning this issue. The E46's LCM is linked with the