2021 Honda Odyssey Problems

What owners report

Complaints on this model year are dominated by the idle stop system, where the engine shuts off at a stop and does not restart reliably, and by infotainment failures where the screen and rear camera drop out with network-loss messages. A separate cluster involves water leaking into the rear of the van and disabling the power tailgate and rear controls. Reports span from very low mileage to past 70,000 miles, and many describe repeated dealer visits without a lasting fix.

1. 1
   Engine

   Engine does not restart after idle stop

   • 29 complaints (20%)
   • median 52,000 mi at 5.1 yrs old (2 state mileage, few)
   • filed 2021–2026

   At stoplights and in stop-and-go traffic the engine shuts off as designed, then fails to restart when the brake is released or the accelerator is pressed. Some owners describe a full shutdown that requires pressing the start button, and a few report the van could not be shifted or turned off for several minutes. Complaints mention software updates, battery replacement and sensor replacement at the dealer, with the symptom returning later; several owners say the dealer could not reproduce or diagnose it. Reported across a wide mileage range in the sample, from near-new to around 72,000 miles, with several owners noting it in hot weather or after long drives.

   5 related service bulletins

   What to check: Ask whether any idle stop software update has been applied and whether the battery has been replaced. During a test drive with the engine warm, stop at a light with idle stop active and confirm the engine restarts promptly.

   2 excerpts from owner complaints in NHTSA records

   “When coming to a complete atop, the engine switches off (the idle stop function), which is ok, but when I release the brake the engine often fails to restart. I’ve replaced the battery but this appears to be a common problem. It’s been happening more now at the end of summer when it’s hot for some reason. I was told there is a similar investigation open: EA25004”

   NHTSA complaint #11757074, filed 2026-08

   “My Honda Odyssey is experiencing an issue where it intermittently fails to restart automatically after coming to a stop and engaging the idle stop feature. Despite following Honda's recommendations, which included applying Service Bulletin 23-008 (updating the PGM-FI Idle Stop Software) and replacing the battery, the problem persists. I've also had the vehicle inspected at two different dealerships, with no resolution. …”

   NHTSA complaint #11615252, filed 2024-09
2. 2
   Electrical system

   Infotainment screen drops out, camera lost

   • 17 complaints (12%)
   • median 41,665 mi at 5.6 yrs old (2 state mileage, few)
   • filed 2021–2026

   The center screen reboots or goes blank and displays messages about network communication being lost or the MOST network turning off, sometimes with a loud crackling or popping from the speakers. While the screen is out, the backup camera, navigation, CarPlay and hands-free calling stop working. Owners describe repeated dealer visits with harness, cable and screen replacements that did not resolve it, and one complaint notes a related recall for the rear camera display. Described as random and intermittent at various mileages and driving speeds, sometimes occurring many times in a single trip.

   Recall 23V431000

   What to check: While the screen is on, check the backup camera in reverse and try CarPlay or navigation. Ask whether the rearview camera recall (23V431000) was performed and whether any screen or harness work has been attempted.

   2 excerpts from owner complaints in NHTSA records

   “There is a message that pops up in our front touch screen panel com.honda.auto.hars has stopped which is not allowing us to use the touchscreen panel.for anything - from making or receiving calls , navigation , etc .. , which makes it hazardous to drive the vehicle on the road & not able to use hands free. We tried factory reset & also using USB drive to update , but the car is not recognizing the USB drive & also says that our system is up-to-date!! We are not able to find a solution . Please help . Advice needed.”

   NHTSA complaint #11675412, filed 2025-07

   “I hear a popping/crackling noise from the speakers then I get complete network loss for my backup camera, my dvd player, my clock, maps etc.System does a report after 5+ minutes. Message displayed before everything goes black is Network Connection Lost and MOST Net Off. This issue is ongoing and seems to happen now every day sometimes multiple times in a driving session. It just started about 2 weeks ago. There is an active recall for this exact issue for 2021 Honda Odysseys but my VIN does not seem to be included.”

   NHTSA complaint #11689851, filed 2025-09
3. 3
   Electrical system

   Water leak disables power tailgate

   • 21 complaints (14%)
   • median 39,414 mi at 4.8 yrs old (2 state mileage, few)
   • 1 mention a crash, fire or injury
   • filed 2022–2026

   Owners report a power tailgate warning on the dash and a tailgate that will not open or close from the fob, dash button or the door itself. In several complaints water was found in the tailgate or rear cargo area, and dealers traced the damage to a failed seal, a body seam or a roof stud that was not sealed, with the power tailgate control unit or rear fuse box corroded. One owner reported the hatch opening on its own while driving, and another could not get it to latch. Reported at various mileages, often after rain, with one complaint at around 32,000 miles and another near 49,000 miles.

   What to check: Cycle the power tailgate several times and look for water stains, damp carpet or corrosion in the rear cargo area and around the tailgate control unit. Ask whether the tailgate or rear fuse box has ever been replaced.

   2 excerpts from owner complaints in NHTSA records

   “It started that all the sensor in our car started to go off. We were told we had a bad battery, even thought we had replaced it new just last year. Once we had the battery checked and alternator. The sensors started to act up again, out tail gate started to malfunction. Wouldn’t automatically close. A few weeks ago driving down the road the tail gate opened and the anti theft system started going off while the car was running and still going. …”

   NHTSA complaint #11652678, filed 2025-04

   “On 28-Dec-2024 I noticed the power tailgate stopped working on my 2021 Honda Odyssey. I tried to press the power tailgate button on the key fob, the button on the driver's side control panel, and the button on the tailgate itself, but none of them works. I did some research online and found out it's a common problem in 2018 to 2021 models and the cause was the failed Power Tailgate Control Unit due to water leakage through the cracks on the vehicle body. …”

   NHTSA complaint #11635334, filed 2025-01
4. 4
   Air bags

   Curtain airbags deploy without a crash

   • 13 complaints (9%)
   • median 8,000 mi at 0.9 yrs old (1 states mileage, few)
   • filed 2021–2025

   One owner described the passenger-side curtain airbags deploying while driving at about 35 mph with no impact, after which the van was still drivable. Other complaints focus on the front passenger seat weight sensor recall, saying the remedy part was not available and the repair had not been completed. A related recall covers a software error that can cause side and side curtain airbags to deploy unexpectedly. Reported on vehicles at low mileage, including one under 10,000 miles; several complaints concern recall notices rather than a failure.

   Recall 24V064000Recall 26V227000Recall 26V3320001 related service bulletin

   What to check: Ask whether recalls 24V064000, 26V227000 and 26V332000 have been completed, and confirm the front passenger airbag indicator reads correctly with an adult in the seat and with the seat empty.

   2 excerpts from owner complaints in NHTSA records

   “The contact owns a 2021 Honda Odyssey. The contact stated that while driving at 35 MPH, the passenger’s side curtain air bags deployed without incident and without warning. An automated security feature in the vehicle called him immediately upon deployment of the air bags. The contact was asked if he needed assistance from authorities and he informed them that he was ok. The contact was not injured during the failure. The contact was able to drive the vehicle home where it remained in his possession. …”

   NHTSA complaint #11429024, filed 2021-08, 8,000 miles

   “The contact owns a 2021 Honda Odyssey. The contact received notification of NHTSA Campaign Number: 24V064000 (Air Bags); however, the part to do the recall repair was unavailable. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the issue. The contact had not experienced a failure. Parts distribution disconnect.”

   NHTSA complaint #11612398, filed 2024-09
5. 5
   Forward collision avoidance

   Forward collision alerts and unexpected braking

   • 31 complaints (21%)
   • median 3,500 mi at 0.5 yrs old (3 state mileage, few)
   • 2 mention a crash, fire or injury
   • filed 2021–2026

   Owners report the forward collision system braking hard with nothing in front of the vehicle, and radar or sensor warnings appearing and staying on after snow or rain. Complaints also describe speed limit signs being misread and lane departure and collision systems going offline, with dealers saying they could not find a fault or attributing the failure to the weather. Reported from very low mileage (a few hundred miles) upward, several times after driving in snow or rain.

   What to check: Drive the van in traffic and note whether the collision warning or braking triggers with a clear road. Check that no sensor or system-off warnings remain lit after startup, and ask whether the radar unit or windshield camera area has been repaired.

   2 excerpts from owner complaints in NHTSA records

   “Hi the vehicle shows speed limit of 70 in 25 or 40mph zones. The vehicles system keeps going offline emergency braking and collision. Every time I take to Honda dealer I am being told to go see where the car was purchased and they can't find a issue.”

   NHTSA complaint #11397134, filed 2021-02, 380 miles

   “On numerous occasions the forward collision warning has caused hard braking when there is nothing close in front of me. I fear that a close following vehicle will hit me when this occurs. This has not caused an accident yet, but the following vehicle driver must think that I'm a terrible driver for unnecessarily hitting my brakes.”

   NHTSA complaint #11465765, filed 2022-05

Buying note. Check that open recalls, particularly the airbag sensor and rearview camera campaigns, have been completed, and test the idle stop restart and the infotainment screen during a drive. Inspect the rear cargo area for water intrusion, since leaks there have left owners with an inoperable power tailgate.

Summary written with AI from a sample of 60 NHTSA complaints for this model year (picked at random, with complaints that state a mileage and recent ones taken first), then checked automatically against the source records. Where a problem shows a complaint count, every complaint for this model year was matched with fixed keyword rules (written with AI and tested against the sample), and the mileage, age and repair figures are calculated from those complaints; owners' figures are as stated, not verified. Other counts refer to the sample. The excerpts come from NHTSA's public complaint records and are unverified; capitalisation is normalised, NHTSA staff notes are removed, and shortened text ends with “…”. Something wrong? Request a correction.