Owners of 2019 Avalons report systemic electrical failures concentrated in the Data Communication Module (DCM). The DCM drains batteries even when the vehicle sits off, leaving drivers stranded unable to start. It disables SOS Emergency Assistance—a genuine safety hazard when drivers need emergency help. It kills Remote Connect (remote lock, unlock, start), displays persistent "Connected Device Not Supported" errors, and emits an ear-piercing high-pitched noise during startup loud enough to concern parents about hearing damage to children and cause ear ringing in adults.
Beyond the DCM, the climate control panel fails completely—no buttons, lights, heat, air conditioning, defroster, or seat heat—then mysteriously works again. Dealerships can't replicate the fault or find codes. The sunroof drains clog repeatedly with organic debris despite recent dealer service, saturating carpets with mold-smelling water. Rear camera detection displays unavailable messages (dealers quote $2,000 with no guarantee). Safety systems are unreliable: blind-spot monitors don't detect vehicles 70% of the time above 40 mph, cross-traffic alerts malfunction, and pre-collision warnings trigger falsely every few months.
One owner reported acceleration hesitation followed by spontaneous acceleration in stop-and-go traffic with no warning lights. Another experienced multiple sensor failures, warning lights, and engine seizure mid-drive requiring a 30-minute restart cycle, followed by repeated warranty claim denials.
Failure modes owners describe
DCM (Data Communication Module) Battery Drain
Defective DCM units drain the vehicle battery even when the vehicle is off, leaving drivers stranded. Multiple owners report inability to restart vehicles due to complete battery discharge.
Symptoms owners cite: Vehicle won't start after sitting; Battery completely drained; Vehicle left stranded
Repairs/costs cited: DCM module replacement required; some owners cited $1,200 cost
DCM Loss of Emergency SOS Functionality
DCM failure disables or impairs SOS Emergency Assistance, preventing drivers from accessing emergency help during critical situations. Owners report inability to use emergency response systems.
Symptoms owners cite: SOS button unresponsive; Emergency assistance unavailable; Red and green lights flashing near SOS button with high-pitched noise
Repairs/costs cited: DCM module replacement required
DCM Loss of Connected Features and System Errors
Remote Connect capabilities (remote start, unlock, vehicle monitoring) become inoperative. System displays 'Connected Device Not Supported' errors and cannot communicate with mobile app or receive software updates.
Symptoms owners cite: Remote Connect app non-functional; Cannot unlock or remotely start vehicle; Cannot update vehicle software; 'Connected Device Not Supported' error messages
Repairs/costs cited: DCM module replacement; $130 diagnostic fee reported
DCM High-Pitched Startup Noise
Extremely loud, high-pitched noise emitted from vehicle speakers during startup, lasting several seconds. Owners report the noise is painful and poses hearing loss risk, particularly concerning to parents of young children. Issue appears across multiple Toyota models.
Symptoms owners cite: Ear-piercing high-pitched noise from speakers on startup; Full-volume noise output; Ears ringing after noise; Red and green lights flashing near SOS button concurrent with noise
Repairs/costs cited: DCM module replacement; $1,200 cost cited
Sunroof Drain Clogging
Driver-side sunroof drains clog with organic debris (leaves, etc.), causing rainwater to overflow into the vehicle interior. Issue recurs within weeks despite dealer clearing. Dealership suggests low mileage causes clogging, though owner disputes this explanation.
When: 140 miles per month driving reported at time of issue recurrence
Symptoms owners cite: Wet carpeting on driver-side floorboard; Heavy mildew smell inside vehicle; Standing water accumulation; Problem recurs less than a month after dealership repair
Repairs/costs cited: Sunroof tray and drains cleared of organic material by dealership; detailer separately cleaned and dried carpet
Recalls/TSBs owners mention: Dealership claims no structural defect; attributes issue to external factors and low mileage
Climate Control Panel Intermittent Failure
Complete failure of climate control panel with no buttons or lights functioning. Affects heating, air conditioning, fan speed, defroster (windshield and mirror), and seat heat. Failures are intermittent and cannot be consistently reproduced; no diagnostic trouble codes stored.
When: 41,400 miles on vehicle
Symptoms owners cite: All climate control buttons non-responsive; All panel lights out; No fan, heat, or A/C operation; Window defroster inoperative; Mirror defroster inoperative; Seat heat inoperative; Intermittent operation; functions normally for periods then fails again; Fails on startup then may recover during drive
Repairs/costs cited: Dealership performed master reset thinking software update was corrupt; no parts replaced
Rear Camera Detection (RCD) System Failure
Rear camera detection system displays unavailable message and stops functioning. Dealership quoted approximately $2,000 repair cost with no guarantee of fix. Owner reports widespread issue affecting thousands of Toyota owners; some fixed by recalibration but many have underlying hardware problems.
When: One year prior to complaint; vehicle was under warranty at time of initial failure
Symptoms owners cite: 'RCD Unavailable' message displayed; Rear camera detection system non-functional
Repairs/costs cited: Dealership quoted ~$2,000; some owners report successful recalibration while others require component replacement
Recalls/TSBs owners mention: Toyota response: 'It's a rolling computer, and very advanced.' No recall or TSB action reported
Acceleration Hesitation and Spontaneous Acceleration
Vehicle hesitates when accelerator is applied in stop-and-go traffic, then spontaneously accelerates. No warning indicators illuminate. Dealership states software update was needed but vehicle was performing as designed.
When: 3,500 miles
Symptoms owners cite: Accelerator pedal applied but vehicle hesitates; Vehicle spontaneously accelerates; Occurs in stop-and-go traffic at various speeds; No warning lights
Repairs/costs cited: Dealership advised software update needed but performed no repair
Recalls/TSBs owners mention: Manufacturer case #1904010349 opened; advised owner to contact local dealer; vehicle stated to be performing as designed
Passenger-Side Blind Spot Monitor Malfunction
Blind spot monitor on passenger side fails to detect vehicles 70% or more of the time, giving false sense lane is clear. Problem worsens during longer drives and becomes nearly unusable above 40 mph. Driver-side system functions correctly.
Symptoms owners cite: Blind spot monitor not detecting vehicles in passenger-side blind spot; False negative alerts (shows lane clear when vehicles present); System degradation during extended driving; Failure rate increases above 40 mph
Recalls/TSBs owners mention: Toyota states system works to specs, but owner contends factory manual shows it does not meet specifications
Pre-Collision System Unreliable Warnings
Pre-Collision warning system light turns on during startup with no actual hazard present. System generates numerous false alarms in vehicle history recorded every few months. Unreliable operation undermines driver confidence in safety feature.
When: 20,000 miles
Symptoms owners cite: Pre-Collision warning light illuminates on startup without cause; Multiple false failure warnings in vehicle onboard history; Failures occur intermittently every few months
Blind Spot Monitor and Cross-Traffic Alert Malfunction
Both blind spot monitoring and cross-traffic alert systems malfunction. Dealer unable to find fault during inspection, but failures persist and recur.
Symptoms owners cite: Blind spot monitoring malfunction alerts; Cross-traffic alert malfunction alerts; Intermittent failures
Recalls/TSBs owners mention: Dealer unable to diagnose
Multiple Sensor and Ignition System Failures
Vehicle experienced multiple electrical sensor failures since July 2025 (noting unusual date, likely transcription error). Owners report numerous warning lights and engine seizure during driving, followed by inability to restart.
When: 46,000 miles; failures began July 2025
Symptoms owners cite: Multiple unknown warning lights illuminated; Engine seized while driving; Vehicle failed to restart initially; Vehicle restarted after 30-minute wait; Anxiety and fear from repeated failures
Repairs/costs cited: Oxygen sensor, oil light sensor, ignition coils, and fuel pump extension replaced
Recalls/TSBs owners mention: Manufacturer made aware; cases filed but all were denied
Synthesized from 15 NHTSA owner complaints — unverified consumer
allegations, summarized for patterns. The verbatim filings appear below.