Recall 20V664 affects 5 2018-2020 Proterra Catalyst buses for loose steering gear box bolts. Repair is free at any franchised Proterra dealer.
Proterra is recalling 5 2018-2020 Catalyst buses because missing plexus adhesive between the torque plate and chassis can let steering gear box bolts loosen. An unsecured steering gear box can cause a driver to lose steering control, increasing the risk of a crash or injury, and Proterra dealers will complete the repair free of charge.
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What's wrong?
The steering gear box on 2018-2020 Proterra Catalyst buses is the part that turns the driver's steering input into movement at the wheels. It is secured to the bus chassis through a torque plate, with bolts holding the gear box in position. That mount has to stay tight so the steering response stays predictable.
On affected buses, the space between the torque plate and the chassis lacks the required plexus adhesive. That adhesive is a bonding layer that helps keep the plate seated against the chassis. Without it, the torque plate can separate during normal service, and the bolts holding the steering gear box can loosen or break free.
There are four bolts holding the gear box in place. If one or more loosen, the steering gear box can move out of position and the bus becomes harder to steer. A driver can notice the warning sign as steering effort increases while driving.
Who's affected?
Spans 3 model years, all involving the same steering gear.
| 2018 Proterra Catalyst | steering gear |
|---|---|
| 2019 Proterra Catalyst | steering gear |
| 2020 Proterra Catalyst | steering gear |
| Units affected | 5 |
| Field incidents | NHTSA has logged 2 field incidents to date. |
The year and model narrow the scope, but the VIN decides. Check your VIN to confirm whether your specific bus is included.
What's the safety risk?
An unsecured steering gear box can leave the driver unable to steer, increasing the risk of crash or injury. Four bolts hold the gear box in place; if they loosen or break free, the gear box shifts and steering gets harder. Schedule the inspection soon. Repair is free at any franchised Proterra dealer.
What should I do?
- Check your VIN to confirm your 2018-2020 Proterra Catalyst bus is included in this recall.
- Contact a franchised Proterra dealer to schedule the free steering gear mounting-bolt inspection and adhesive repair that keeps the steering gear box secured to the chassis.
- Ask Proterra customer service at 1-864-438-0000 if you need scheduling help, and reference recall number 20V664.
- Bring the recall notice if Proterra mailed one, or give the dealer recall number 20V664 at intake.
- Avoid unnecessary driving until the inspection and repair are complete.
What happens at the repair
At the dealer, a Proterra technician inspects the steering gear mounting bolts and checks the plexus adhesive layer between the torque plate and the chassis. If the adhesive layer is missing or not thick enough, the technician repairs the affected components. The recall repair is free, and parts and labor are covered. Because the remedy is available, contact a Proterra dealer or service center and ask them to confirm the inspection and repair procedure for recall 20V664 before bringing the bus in.
Timeline
| October 28, 2020 | NHTSA published the recall |
|---|---|
| December 10, 2020 | Owner notification mailed |
| December 28, 2020 | Dealer notification began |
| December 28, 2020 | Dealer notification ended |
| December 28, 2020 | Interim owner notification (was planned for this date) |
Frequently asked questions
What is recall 20V664?
Recall 20V664 covers 5 2018-2020 Proterra Catalyst buses where missing plexus adhesive between the torque plate and chassis can let steering gear box mounting bolts loosen. An unsecured steering gear box can lead to loss of steering. Proterra dealers inspect and repair the mounting area for free.
What should I do if my 2018-2020 Proterra Catalyst is on this recall?
Check your VIN to confirm your specific bus is included in recall 20V664. If it is, contact a Proterra dealer or Proterra customer service at 1-864-438-0000 to schedule the steering gear mounting bolt and adhesive inspection. Reference Proterra recall number SC-20-154 when you call.
Is the recall repair free?
Yes. Federal recall law requires the manufacturer to repair the defect at no cost, and Proterra dealers will inspect the steering gear mounting bolts and plexus adhesive layer for free. If the adhesive is missing or insufficient, the repair is covered.
What is the safety risk?
The safety risk is loss of steering control. If the steering gear box is not secured to the chassis, the driver can lose the ability to steer the bus, increasing the risk of crash or injury. The remedy is a free dealer inspection and repair.
When did the Proterra Catalyst recall begin?
Proterra began this recall on December 10, 2020. Owners of affected 2018-2020 Catalyst buses were directed to have a dealer inspect the steering gear mounting bolts and adhesive layer, then repair the components for free if the adhesive was missing or insufficient.
More information
| NHTSA campaign page | nhtsa.gov/vehicle-recalls/20V664000 |
|---|---|
| Proterra customer service | 1-864-438-0000 |
| NHTSA recall # | 20V664 |
| NHTSA recall # (full) | 20V664000 |
Source documents
-
Download Misc. Document (PDF) - Download Owner Notification Letter (PDF)
- Download Recall Report (PDF)
- Download Quarterly Report (PDF)
- Download Recall Acknowledgement (PDF)
This article is generated from NHTSA's primary recall filings and reviewed against the source on May 24, 2026. RecallNotify does not paraphrase NHTSA's consequence language; that text is reproduced as written above. Editorial standards →