NHTSA Service Bulletin 10201621: 2022 Blue Bird All American School Bus
Official manufacturer communication context for 2022 Blue Bird All American School Bus, with affected products, buyer checks and links into Carchieve recall, problem and VIN research.
Reviewed June 2026 from NHTSA manufacturer communication and service bulletin records. Carchieve is independent and not affiliated with any vehicle manufacturer or government agency.
The intent of Service Update SU2105 is to provide service notification of a running product improvement part change to the relay used for diesel exhaust fluid (DEF) line heaters. The new DEF line heater relay will be "Diode Suppressed". The new relay change is being made to improve circuit fault diagnostic capabilties. This change implements two new diode suppressed relay part numbers based on bus model application. The new relays are easily distinguishable by color. They have a yellow high temp tape wrap. Models Affected: Vision (BBCV), All American, and TX4 (T3FE, T3RE), with EPA/CARB certified on highway Cummins Diesel Engine Features Built After 07/26/2021 Subject: The intent of Service Update SU2105 is to provide service notification of a running product improvement part change to the relay used for diesel exhaust fluid (DEF) line heaters. Information: The new DEF line heater relay will be "Diode Suppressed". The new relay change is being made to improve circuit fault diagnostic capabilities. This change implements two (2) new diode suppressed relay part numbers based on Blue Bird bus model application. The new relays are easily distinguishable by color. They have a yellow high temp tape wrap. New Diode Suppressed Relay Type, Part Number, And Application: Diode Suppressed Micro Relay 10073451 All American and TX4 (T3FE, T3RE) with Cummins Diesel Engine Features Built After 07/26/2021 Diode Suppressed Mini Relay 10073452 Vision (BBCV) with Cummins Diesel Engine Features Built After 07/26/2021
What this bulletin may mean before buying
Treat this as service research, not a verdict on one car. Before you buy, compare this communication with official recall campaigns, model-level owner complaint patterns, and the exact vehicle’s VIN-decoded specifications. A bulletin can help you ask a seller or dealer sharper questions about software updates, known repairs, warranty extensions and service history.
Affected products listed in this communication
Buyer checklist
- Run the 17-character VIN and confirm the year, make, model, engine and equipment match the listing.
- Check recall campaign pages for safety actions that may require dealer repair.
- Compare this bulletin with common problem pages for the same model and component area.
- Ask the seller or dealer whether the bulletin procedure, update or inspection has already been completed.
- Use the used-car buying checklist and get an independent inspection.
Frequently asked questions
What is NHTSA service bulletin 10201621?
The intent of Service Update SU2105 is to provide service notification of a running product improvement part change to the relay used for diesel exhaust fluid (DEF) line heaters. The new DEF line heater relay will be "Diode Suppressed". The new relay change is being made to improve circuit fault diagnostic capabilties. This change implements two new diode suppressed relay part numbers based on bus model.
Is a service bulletin the same as a recall?
No. A recall is a safety campaign with a required remedy for affected VINs. A service bulletin or manufacturer communication usually describes diagnostic, repair, software, warranty or service information.
How should a used-car buyer use this bulletin?
Use it as a research signal. Compare it with recalls, owner complaints, service records, a VIN report and an independent inspection before buying.
Check the exact VIN before you buy
Model-level pages show public safety patterns. A full VIN report helps confirm the exact vehicle, decoded specs, recall applicability and buyer checks.
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