The 2006 Avalon shows brake system problems across multiple failure modes. The most common involves the brake master cylinder seal leaking, draining the brake fluid reservoir and leaving the driver with a mushy or non-responsive pedal. Owners at 39,000 to 108,000 miles have experienced complete brake loss at highway speeds and during normal driving, sometimes resulting in collisions. Toyota issued recall 10V499000 to replace the master cylinder seal with a redesigned part at no cost, but some owners report their replacement seals failed again within three years.
A second pattern involves unintended acceleration with simultaneous brake failure. Multiple owners describe the engine suddenly revving while their foot is on the brake at traffic lights or during normal driving. Pressing the brake harder does not stop the acceleration. Dealers have performed various modifications—computer reprogramming to override engine acceleration with brake input, brake master cylinder modification, or accelerator pedal replacement—but the root cause is often unclear.
A third group of owners report the brake pedal simply not working despite firm depression, occurring from 5 mph to highway speeds. These failures have resulted in rear-end collisions, intersection crashes, and one severe crash into trees. One owner's brake caliper froze in 2012, was repaired, then froze identically in 2015. Dealership responses vary; some cannot identify the failure, others cite leaking master cylinders requiring replacement, and some claim the failure is outside warranty coverage despite the vehicle being only a few years old.
No clear pattern of fix-and-stay-fixed emerges from these narratives.
Failure modes owners describe
Brake master cylinder seal failure / brake fluid loss
Brake fluid leaks from faulty master cylinder seals, leading to partial or total loss of braking pressure. Owners report the brake fluid reservoir emptying, brake pedal losing resistance or traveling to the floor, and inability to stop the vehicle.
When: 39,000 miles (2 yrs 9 months), 48,000 miles, 53,000 miles, 55 mph incident, 108,000 miles
Symptoms owners cite: Brake light illuminates; Brake pedal feels mushy or loses resistance; Brake pedal travels to the floor; Brake fluid reservoir empty; Vehicle will not stop or stops slowly; Grinding noise on rough surfaces with failed brake response; Brake pedal vibrates
Repairs/costs cited: Dealers replace master cylinder seal, master cylinder, and/or brake booster. One owner cited $1,250 repair estimate for master cylinder and booster; another reported replacement of reservoir, brake booster, and master cylinder. One owner replaced the seal under recall 10V499000 in April 2012, but the new seal failed again in April 2015 (3 years later) at 53,000 miles, covered only by 12-month component warranty.
Recalls/TSBs owners mention: Recall 10V499000 (Service Brakes, Hydraulic: master cylinder seal) — dealers replace seal with newly designed one at no charge. One owner reported the VIN was not included in the recall list despite experiencing the same failure. Toyota denied coverage on replacement seal that failed after 3 years.
Unintended acceleration with brake override failure
Engine unexpectedly revs or vehicle accelerates while driver has foot firmly on brake. Brake pedal does not prevent acceleration; pressing harder on brake does not stop the car. Multiple incidents occurred at traffic lights and during normal driving at low to moderate speeds.
When: 9,500 miles, 28,000 miles, low speed (5 mph, 30 mph), during first year of ownership, 2010-2012 timeframe
Symptoms owners cite: Engine suddenly revs or surges; Vehicle accelerates despite brake pedal depressed; Brake pedal pressed harder but car continues to accelerate; RPMs increase while brake is applied; Car moves forward at traffic light or intersection despite foot on brake
Repairs/costs cited: Dealers performed modification to brake master cylinder or replaced accelerator pedal and brakes. One owner stated dealer was unable to locate the failure but modified the brake cylinder anyway. One owner reported that recalls (mat, gas pedal) were performed; another had computer reprogrammed to allow brakes to override engine.
Recalls/TSBs owners mention: Toyota performed recall actions including floor mat checks and computer reprogramming to allow brakes to override everything else. One owner reported filing complaint with manufacturer; another had SUA (sudden unintended acceleration) incident form filed but received no written results explaining what was found or corrected.
Brake pedal unresponsiveness at various speeds
Brakes fail to engage or provide poor stopping power when brake pedal is depressed, even with extreme force. Occurs at speeds ranging from 5 mph to 55 mph. Some incidents resulted in collisions.
When: 11,382 miles, 20,000-150,000 miles range, 25 mph, 48,000 miles, 55 mph, 75,000 miles, 108,000 miles
Symptoms owners cite: Brake pedal does not engage or responds poorly; Vehicle fails to stop despite pedal depression; Pedal requires extreme pressure to achieve any braking; Must pump brakes to achieve stopping power; Brakes unresponsive over rough surfaces or potholes
Repairs/costs cited: One owner pumped brakes to stop after brake warning light; crash into intersection and trees followed, requiring extrication. Another owner crashed into rear of another vehicle; injuries reported. Another crashed into cement barrier; no serious injury. Repair details sparse; one case diagnosed as leaking master cylinder requiring replacement, but failure recurred.
Recalls/TSBs owners mention: Recall 10V499000 referenced by multiple owners. One owner's VIN was not included in recall list despite experiencing brake failure. One owner reported Toyota claimed failure outside component warranty (12 months); no safety concern acknowledged.
Brake caliper freeze / piston retraction failure
Front brake caliper piston does not retract, freezing the caliper and destroying brake pads, resulting in no braking function.
When: 2012 (first occurrence), April 2015 (recurrence at 58,000 miles)
Symptoms owners cite: Right front caliper freezes; Piston does not retract; Brake pads destroyed; No braking as a result
Repairs/costs cited: Same caliper repaired in 2012; identical failure occurred again in April 2015. Repair involved caliper service but underlying cause not addressed.
Brake pedal pushback / soft pedal feel
Brake pedal feels like it pushes back toward driver as vehicle comes to full stop, creating sensation that car may not stop. Pedal may require full depression to achieve adequate braking.
When: As vehicle approaches full stop
Symptoms owners cite: Brake pedal pushes back toward driver; Feeling that car will not stop; Brake pedal mushy or lacking firmness; Must press brake pedal all the way to slow down
Repairs/costs cited: One owner brought vehicle to dealership; mechanic observed the issue but could not determine the cause. No repair documented.
Synthesized from 23 NHTSA owner complaints — unverified consumer
allegations, summarized for patterns. The verbatim filings appear below.