Crosstrek Defroster Failure: Both Front & Rear Dead

I had a very similar issue with my 2015 Subaru Impreza last winter. Having some experience with basic car maintenance, I initially checked the fuses, but that wasnt the problem. The symptoms were identical, the window demister and front heating coil systems stopped working simultaneously. After a complete diagnostic at my regular workshop, they found the battery was severely discharged and damaged several electrical components, including the window heater system. The fix involved replacing the battery and resetting the car defrost control module. Total repair cost was 290€, including parts and labor. The car has been working perfectly since then, with both the rear window heating and front defroster performing as they should. Before suggesting more specific solutions, could you share: Did you notice any other electrical issues before this happened? Have you checked the battery voltage? How old is your current battery? Are there any other warning lights on the dashboard? These details would help determine if youre dealing with the same root cause as I did.

Thanks for sharing your experience. My XV Crosstrek has 64019KM and had its last service 3 months ago. No other electrical issues noticed before the thermal window problems started. Battery is fairly new, replaced just 8 months ago, and voltage reads normal. No other warning lights showing on the dash. The heating coil system issues seem different from your case, especially since both the rear window demister and front defroster started acting up right after that cold snap we had. Had the battery checked specifically because of your suggestion, but readings are all normal. Starting to think it might be related to the defrost control module itself rather than a power issue. Has anyone else dealt with a faulty control module? Wondering about repair costs before heading to the shop.

Thanks for those additional details. Since your battery and electrical system are checking out fine, this does seem different from my initial diagnosis. After similar heating issues continued in my Crosstrek even after battery replacement, I discovered the auto defrost control module was indeed the culprit. The heating coil system malfunction in my case turned out to be tied to a faulty control module that was damaged during extreme temperature changes. The repair involved replacing the control module and recalibrating the car defrost system. Total cost came to around 450€, which was more than the battery-related fix but solved the issue permanently. Key signs that pointed to the control module in my case: Both front and rear defroster failing simultaneously, Normal battery readings, Issues appearing after sudden temperature changes, No other electrical problems One thing to check: are you getting any specific error codes? In my case, the module replacement was definitely needed once the diagnostic showed error code B2XXX (cant remember exact numbers) related to the heating system. Given your symptoms match my second repair experience so closely, you might want to have the shop specifically check the defrost control module when you bring it in.

Since the front defroster and rear window heater are both affected, your suggestion about checking the defrost control module makes a lot of sense. Your experience matches my situation perfectly, especially the timing with the cold weather changes. The error code Im getting starts with B2, though I need to double check the exact numbers. Its really helpful knowing the heating issue was resolved with a module replacement in your case. The 450€ repair cost gives me a good baseline for what to expect. Ill get the car booked in and have them focus on the control module rather than wasting time checking the battery system again. Will probably schedule the repair next week since the window demister problems are making winter driving pretty challenging. Really appreciate everyone sharing their experiences, helps narrow down the problem and avoid unnecessary diagnostic costs at the shop. Just to be thorough, Ill ask them to run a full check on the thermal window systems while its in there. Better to catch any related issues while theyre already working on the car defrost components.