The worst 2021 Kenworth T800B problems
Ranked by number of owner complaints. Mileage and cost come from what owners wrote.
Problems by type
Tap a problem to see which part fails, at what mileage and in which other years.
Recalls 5
Electrical system: software
- What is wrong
- PACCAR Incorporated (PACCAR) is recalling certain 2021-2025 Peterbilt and Kenworth vehicles, equipped with Bendix EC80 Advanced Electronic Control Units (ECU). Please see the recall report for a complete list of models. Electrical noise and low signal to the power line carrier may cause the ECU to incorrectly process commands or stop functioning.
- Risk
- Safety systems that depend on the ECU (Automatic Traction Control, ABS, Electronic Stability Control, Active Cruise Control, and Collison Mitigation System) may not function properly or at all, increasing the risk of a crash.
- Remedy
- Dealers will reprogram the ECU software, free of charge. Owner notification letters were mailed February 3, 2025. Owners may contact Kenworth's customer service at 1‑425‑828‑5888 and Peterbilt's customer service at 1‑940‑591‑4220. PACCAR's numbers for this recall are 24KWL and 24PBL.
Recall number 24V915000 · Recall details
Seat belts
- What is wrong
- PACCAR Incorporated (PACCAR) is recalling certain 2020 Kenworth T660, 2018-2024 Kenworth T800 and W900 vehicles. An additional spacer may have been added to the joint that connects the seat to the seat belt tether and buckle, causing an unsecured connection.
- Risk
- An unsecured seat belt connection may not properly restrain an occupant during a crash, increasing their risk of injury.
- Remedy
- Dealers will inspect and remove the additional spacer and replace the bolt, as necessary, free of charge. Owner letters were mailed March 20, 2024. Owners may contact PACCAR's customer service at 1‑425‑828‑5888. PACCAR's number for this recall is 23KWK.
Recall number 23V717000 · Recall details
Fuel system, diesel: fuel injection system: fuel rail
- What is wrong
- PACCAR Incorporated (PACCAR) is recalling certain 2018-2021 Peterbilt 337, 348, 365, 367, 520, 567, Kenworth T270, T370, T440, T470, T800 and T880 vehicles. The sealing washer may not seat correctly in the pilot bore holes, allowing the high pressure fuel rail assembly to leak.
- Risk
- A fuel leak in the presence of an ignition source increases the risk of a fire.
- Remedy
- Dealers will inspect the rail threads and fuel lines, and replace the rail as necessary, free of charge. Owners may contact PACCAR customer service at 1‑425‑828‑5888 (Kenworth) or 1‑940‑591‑4220 (Peterbilt). PACCAR's numbers for this recall are 21KWC and 21PBD.
Recall number 21V391000 · Recall details
Engine
- What is wrong
- PACCAR Incorporated (PACCAR) is recalling certain 2021-2022 Kenworth T680, T880, W990, T800, W900 and Peterbilt 579, 567, 389, 367 vehicles equipped with a Cummins X15 engine. The capscrews that attach the flywheel to the crankshaft may have been improperly torqued, allowing the flywheel to detach.
- Risk
- A detached flywheel can cause loss of drive power, increasing the risk of a crash. Additionally, driveline pieces may be ejected from the engine compartment, increasing the risk of injury.
- Remedy
- PACCAR will notify owners, and dealers will properly torque the capscrews and the engine will also be inspected for damage and, if necessary, repaired, free of charge. The recall began on March 29, 2021. Owners may contact PACCAR customer service at 1‑425‑828‑5888 (Kenworth) or 1‑940‑591‑4220 (Peterbilt). PACCAR's numbers for this recall are 21KWA and 21PBB.
Recall number 21V080000 · Recall details
Power train: axle assembly
- What is wrong
- PACCAR Incorporated (PACCAR) is recalling certain 2020-2021 Peterbilt 348, 365, 367, 389, 520, 567 and Kenworth T800, T880, W900, W990 vehicles equipped with Watson and Chalin steerable lift axle suspension systems (model SL2065). The axles may have lower rear pivot bolts that are not long enough to sufficiently engage the locking feature of the corresponding nuts.
- Risk
- The short screws can cause the hardware to separate from the suspension system and become road hazards, increasing the risk of a crash and/or injury.
- Remedy
- PACCAR will notify owners, and dealers will inspect suspect chassis and replace the pivot bolts, as necessary, free of charge. The recall began September 29, 2020. Owners may contact Kenworth customer service at 1‑425‑828‑5888 and Peterbilt customer service at 1‑940‑591‑4220. PACCAR's numbers for this recall is 20PBE and 20KWC.
Recall number 20V506000 · Recall details
Technical service bulletins for the 2021 Kenworth T800B 30
Bulletins tell dealers how to fix known problems. A warranty extension means the manufacturer pays for that repair for longer.
- Certain chassis equipped with an engine model year 2019
- This optional software update is expected to be available after 10/30/2026 for chassis equipped with EMY...
- Due to supplier constraints, an authorized aftermarket surge tank has been made available.
- Kenworth: Dealers should check the chassis list and SIR weekly for VIN changes
- The verbiage in the Introduction section has been updated.
- The attached procedures document has been updated with more detail and explanations
- Bogie Crossmember Torque Value Update
- Procedure pictures updated for clarity
- Certain C500/T440/T470/T660/T680/T800/T880/W900 chassis may have air tank reservoirs that do not meet air...
- Safety Recall Repair parts and procedures are now available
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Questions about the 2021 Kenworth T800B
Is the 2021 Kenworth T800B reliable?
Owners have filed 0 complaints about the 2021 Kenworth T800B.
What is the most common problem with the 2021 Kenworth T800B?
There are not enough complaints to tell.
How many recalls does the 2021 Kenworth T800B have?
5 recalls, covering electrical system, seat belts and fuel system, diesel.
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