AI DamageThor Motor Coach Tranquility: problems, complaints, bulletins
Summary for the Thor Motor Coach Tranquility across 5 model years: 4 owner complaints and 12 NHTSA service bulletins, plus repair videos. Pick a year for details.
Model years
What fails most often
- 1 Electrical system 75% of all complaints
- 2 Equipment 25% of all complaints
- Electrical system: 3 complaints (75% of all); manufacturer bulletins for this component: 2.
- Equipment: 1 complaints (25% of all); manufacturer bulletins for this component: 1.
Components owners complain about
| Component | Owner complaints | involving a crash | Technical service bulletins (TSB) |
|---|---|---|---|
| Electrical system | 3 | 0 | 2 |
| Equipment | 1 | 0 | 1 |
| Backover prevention | 0 | 0 | 4 |
| Seats | 0 | 0 | 4 |
| Seat belts | 0 | 0 | 2 |
| Steering | 0 | 0 | 2 |
| Structure | 0 | 0 | 2 |
| Other | 1 | 0 | 8 |
What owners report
Short excerpts of NHTSA complaints in the original wording. These are owner statements not verified by NHTSA; personal data removed.
Replaced secondary alternator 3 times. I am using a DC-DC charger from chassis battery now.
The aux alternator installed to charge the house battery is failing, making noise and almost starting the motorhome on fire. A quick search found EVERYONE with the Thor motorhomes with this alternator is having the same issues and Thor will do nothing about it.
The grey water tank empty valve hangs close to the road without support. Mine fell off somewhere while driving cross country. This has happened to many owners and I believe it poses a highway safety hazard.
When owners complained
NHTSA complaints by filing year. The peak shows at what age the problems show up most.
What to check before buying
- Electrical system. Scan all modules, test the battery and alternator, inspect connectors near the impact zone.
- Backover prevention. Rear camera and parking sensors after a rear impact.
- Seats. Occupant sensor, power adjustment, seat mounts.
- Seat belts. Belt pretensioners after airbag deployment, SRS codes.
Manufacturer service bulletins
Bulletin titles as filed with NHTSA.
- Thor Motor Coach (TMC) has been made aware of an emergency WARNING label adhered in error to the interior…
- Thor Motor Coach (TMC) has been made aware of an emergency WARNING label adhered in error to the interior…
- The interior lower panel of the sliding door may become loose and pull or warp away from the chassis…
- The seatbelts for the rear, side facing seats may be too long for some passengers
- Wood stiles are delaminating due to the vendor changing the glue used for the wrapped stiles
- On certain Mercedes-Benz Sprinter vans, the MBUX multimedia system software might not meet specifications
- On certain Mercedes-Benz Sprinter vans, the MBUX multimedia system software might not meet specifications
- MBAG has determined that on certain Mercedes-Benz Sprinter vehicles that are equipped with electrically…
- MBAG has determined that on certain Mercedes-Benz Sprinter vehicles that are equipped with electrically…
- On certain Model Year 2020 Sprinter vehicles, the screws for the front door hinges may not have been…
- Model/Model Year to Add
- It has been determined that on certain Mercedes-Benz Sprinter vehicles, the hydraulic power steering…
Other models of this make
Read also
Sources: public NHTSA data (USA): service bulletins and owner complaints; YouTube: links to videos credited to their authors. Complaints are owner statements not verified by NHTSA, and describe defects rather than crash damage. Data updated 2026-11-05.