2018 Subaru Impreza owners report a cluster of electrical issues that can leave you stranded or worse. The most frequent complaint is repeat battery failure—some vehicles have gone through three or four replacements before reaching 15,000 miles. Owners cite a parasitic drain linked to the Data Communications Module (DCM) that keeps trying to connect via outdated 3G cell service and won't let the battery recharge properly. One owner had to install an aftermarket battery tender just to keep the car functional.
Infotainment and display malfunctions also appear regularly: the factory head unit (Starlink, HK-produced) randomly powers off and on, won't hold Bluetooth pairing, and the backup camera display goes black or is slow to activate. One owner reports the display hasn't even responded after a recall update was supposed to fix it.
Less frequent but serious failures include a cracked ignition coil that triggered a complete engine shutdown while driving, an ignition switch that won't engage properly, and a confirmed starter motor failure. One owner's side airbags didn't deploy during a collision because electrical faults prevented the sensors from firing. Dashboard lights flicker severely enough to hamper visibility, and some owners report loss of power when driving uphill alongside these electrical gremlins. Multiple owners note Subaru dealerships have been slow to address the root causes and reluctant to escalate issues as recalls.
Failure modes owners describe
Parasitic battery drain / Data Communications Module (DCM) failure
Battery fails repeatedly within weeks of replacement, car won't hold charge and strands owner. Dealership testing identified the DCM as the parasitic load source; DCM is attempting to phone home via deprecated 3G service that no longer exists.
When: As early as 2 years into ownership; by 14k–50k miles some vehicles on their 3rd–4th battery by 2021
Symptoms owners cite: Battery dead or near-dead after a few days of non-use; Unable to jump-start in some cases; Car completely unresponsive, cannot start
Repairs/costs cited: Dealership replaced OEM battery multiple times (up to 4 replacements per owner); one owner installed battery tender; DCM fuse pulled as temporary fix; DCM and DCM battery back-ordered or replaced under extended warranty when available
Recalls/TSBs owners mention: Subaru consumer advocate suggested aftermarket battery tender; some owners had extended warranty cover DCM replacement; no formal recall announced
Infotainment head unit (Starlink/HK) malfunction
Factory head unit randomly powers on and off, loses Bluetooth pairing, and exhibits unresponsive behavior. Issue persists even after WUA86 software update recall in 2019.
When: Post-recall in 2019; complaints logged 2021–present
Symptoms owners cite: Head unit randomly turns off and on; Bluetooth will not connect or randomly disconnects; USB/music interface not recognized; Backup camera display slow to activate or goes black; Power button ineffective; unit won't stay off
Repairs/costs cited: Unit was reprogrammed/updated in 2019 under recall; issue recurred post-repair; no follow-up parts or reprogramming documented
Recalls/TSBs owners mention: WUA86 software update recall performed 2019; same issues reported after
Cracked ignition coil
Ignition coil failure at low mileage caused engine to stall and shut down completely while driving uphill. Owner notes there were two recalls related to this issue but the root cause was not addressed until sudden failure.
When: Relatively low mileage; owner notes ignition coils typically last 80k–100k miles
Symptoms owners cite: Engine hesitation and stuttering/sputter when driving uphill; Power loss during acceleration; Engine stalls without warning; Simultaneous dashboard warning lights illuminate; Complete engine shutdown while driving
Repairs/costs cited: Cracked coil replaced; battery was also found dead at same incident
Recalls/TSBs owners mention: Two recalls related to this issue exist but owner reports unclear explanation of root cause or ongoing risk
Ignition switch engagement failure
Ignition key stuck or very difficult to turn; owner had to manipulate key repeatedly over months to get engine to turn over.
When: Intermittent over several months prior to complaint
Symptoms owners cite: Key won't turn in ignition or resistance is high; Requires repeated manipulation to engage starter
Starter motor failure
Starter motor failed without warning, rendering vehicle unable to start. Mechanic indicated this was the third such failure he had seen on 2018 Imprezas.
When: No prior symptoms; sudden failure at unspecified mileage
Symptoms owners cite: Car struggled to turn over earlier in day; Sudden complete inability to start; No warning lights reported
Repairs/costs cited: Starter motor replaced by independent mechanic; confirmed faulty
Dashboard and headlight flickering
All dashboard lights flicker uncontrollably, reducing visibility noticeably. Flickering worsens during acceleration and correlates with a shimmy felt throughout the vehicle. Owner fears headlights will fail completely.
When: Prior to complaint; over 2 years since related headlight recall
Symptoms owners cite: Nonstop flickering of all lights; Vehicle shimmy synchronized with light flicker; Flickering increases during acceleration; Reduced headlight output/visibility
Repairs/costs cited: Dealership states parts unavailable or ignores repair requests
Recalls/TSBs owners mention: Headlight recall exists but parts unavailable at dealership
Backup camera/display malfunction
Rear camera display goes black or is very slow to appear when reversing. Owner can only see guideline overlay, no actual camera feed.
When: Recurring since January 2021
Symptoms owners cite: Display screen goes black when reverse is activated; Only red and yellow guide lines visible; No camera image displayed; Extended delay before image appears
Automatic headlight dimmer failure
Automatic dimming function for headlights stopped working and has not been repaired.
When: Noticed post-battery replacement; still not functional at time of complaint
Symptoms owners cite: Automatic dimmer will not engage
TPMS (tire pressure monitoring system) sensor false warning
Low tire pressure warning lamp illuminates repeatedly despite vehicle being serviced twice for the issue. Owner has open case with Subaru of America.
When: Recurring issue; serviced twice without resolution
Symptoms owners cite: Low tire pressure warning remains on persistently; Warning returns after service visits
Repairs/costs cited: Serviced twice; unresolved
Recalls/TSBs owners mention: Open case with Subaru of America; no resolution reported
Airbag sensor failure due to electrical fault
Side airbags failed to deploy during a collision. Airbag control sensors were triggered but the electrical system did not fire the airbag due to electrical problems.
When: At time of collision
Symptoms owners cite: Side airbags did not deploy on impact; Airbag sensors activated but airbag module did not respond; Undeployed airbag failed to provide safety protection
Synthesized from 11 NHTSA owner complaints — unverified consumer
allegations, summarized for patterns. The verbatim filings appear below.