Smart Fortwo Electrical Glitches Point to Bad Rain Sensor

Had the same electrical fault symptoms on my 2008 Smart ForFour CDI. The bubbling under the windshield gel pad where the rain detection sensor sits was causing multiple electronic malfunctions. The root cause was moisture penetration through deteriorated sealing, affecting the auto sensor cluster. This created false signals to multiple car components including the wipers, light control module, and dashboard electronics. The repair required: Complete removal of the old sensor pad, Cleaning and drying of the mounting surface, Installation of a new rain-light sensor unit, Full sensor calibration of the new component, Resealing with proper automotive grade adhesive This was a serious issue as moisture damage can spread to other electronic modules if left unrepaired. The entire job took around 4 hours at the shop. The sensor cluster is an integrated unit, so partial repairs are not possible. For your Smart ForTwo, the symptoms match exactly. Would recommend getting it checked soon before moisture causes additional electrical system damage.

Thanks for sharing your experience. I have these issues fixed about 6 months ago and they havent come back since. The symptoms match perfectly with what I experienced. My Smart Fortwo also had that failing sensor cluster causing unusual electrical faults. Did you remember how much the complete repair cost you? Mine was quite expensive with the sensor calibration and all the related work. Also curious if you noticed any other electronic quirks popping up after the fix?

The total fix at my shop came to 62€ for addressing those bubbles under the gel pad. Much more reasonable than I expected. Since having the rain-light sensor properly repaired and calibrated, all electrical fault issues completely cleared up. The auto sensor cluster now works perfectly, no more unusual wiper activation or headlight problems. The repair definitely solved all those annoying electrical gremlins I mentioned in my first post. No new quirks or sensor faults have appeared in the months since. The key was making sure the mounting surface was completely dry and properly sealed to prevent any future moisture issues with the car components. A proper sensor calibration after installation really makes a difference in how well these electronic systems function together. It sounds like your repair experience was more costly than mine. Different shops often have varying rates for this type of specialized electrical work.

Thanks for checking back! Finally got this resolved last week. Took it to a different mechanic who actually specialized in Smart car electronics. Total repair came to 420€ including parts and labor, higher than expected but worth it to fix all those electrical gremlins. The malfunctioning sensor was exactly the culprit. They found water damage around the entire sensor cluster that was causing those unusual electrical faults. The mechanic showed me how the old sealing had completely deteriorated, letting moisture affect multiple car components. The repair process was pretty extensive: Full removal and replacement of the sensor cluster, Complete resealing of the mounting area, System-wide calibration of all affected auto sensors, Testing of all electrical systems Everything works perfectly now, no more unusual headlights, proper wiper function, and all dashboard electronics back to normal. Really glad I got it sorted before the moisture could cause more extensive damage to other electrical systems. The mechanic recommended checking the seals around other sensors annually to catch any deterioration early. Good preventive advice that might help others avoid similar issues.