The contact was the operator of a 2026 Peterbilt 579 for an employer. The contact stated that whether driving 30 MPH or 65 MPH, after another vehicle entered the lane in front of the vehicle, the Forward Collision Avoidance: AEB and Lane Keep Assist systems erroneously activated and brought the vehicle to an unsafe and abrupt stop. The contact stated that the RADAR system had experienced a False Positive alert of a possible crash, even though the vehicle was at a safe driving distance ahead. The contact stated that the failure caused other driver’s behind the vehicle to run off the road or skid to a stop to avoid crashing into the rear of the vehicle. The contact stated that the failure also occurred with another vehicle approximately 100-feet ahead coming over into the lane, and the AEB activated, causing the wheels to lock up, bringing the vehicle to an abrupt stop. The contact stated that other drivers angrily honked at him. On one occasion, the contact was followed by an irate driver for ten minutes after the failure had occurred. The contact was concerned for his safety and the safety of the public because the system could not be overridden. The contact stated that on one occasion while his brother was driving the vehicle at a moderate speed, while the contact was asleep in the sleeping netting which the contact believes was not DOT approved, the AEB system activated and sent the contact’s body forward, causing his rib cage to strike a cabinet inside the sleeper berth, causing an injury. The contact had not sought medical attention. The contact stated that the employer was notified of the failures with the vehicle, and the contact was informed to keep driving the vehicle as-is or seek other employment. The contact stated that the RADAR system also experienced False Positive alerts and inadvertent AEB activation while driving and approaching bridges or structures that cast shadows onto the roadway bringing the vehicle to an abrupt stop. The contact stated that prior to the abrupt stop, there was a picture of
The worst 2026 Peterbilt 579 problems
Ranked by number of owner complaints. Mileage and cost come from what owners wrote.
- Brakes1
Problems by type
Tap a problem to see which part fails, at what mileage and in which other years.
- Brakes1
Recalls 2
Service brakes, air: supply: quick release valve
- What is wrong
- PACCAR Incorporated (PACCAR) is recalling certain 2026-2027 Peterbilt 579 and 2027 Kenworth T680 tractors. The trailer air connection quick release (QR) valve in the air brake system may have been incorrectly installed, which can cause the trailer to become unstable after the driver applies the brakes. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 121, "Air Brake Systems."
- Risk
- An incorrectly installed quick release valve that does not function properly can increase the risk of a crash.
- Remedy
- Paccar inspected and reinstalled the valves, as necessary, free of charge. All affected tractors have been repaired and therefore no owner notification letters are necessary. Owners may contact Peterbilt's customer service at 1‑940‑591‑4220 and Kenworth's customer service at 1‑425‑828‑5888. PACCAR's number for this recall is 26PACC.
Recall number 26V442000 · Recall details
Exterior lighting: lighting control module: software
- What is wrong
- PACCAR Incorporated (PACCAR) is recalling certain 2024-2026 Kenworth T480, T680, T880, W990, Peterbilt 520, 536, 537, 548, 567, 579, 589, 2025 Kenworth T180, Peterbilt 535, 2025-2026 Kenworth T280, T380 and L770 vehicles. The tail brake light, upper and lower beam headlights, reverse light, and turn signal may not illuminate as intended. In addition, the lift axles, if lowered, may revert to a raised position, or oscillate up and down when the signal warning lights are activated. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) number 108, "Lamps, Reflective Devices and Associated Equipment."
- Risk
- Delayed and unsteady headlights can result in insufficient illumination of the road, decreasing the driver's visibility and increasing the risk of a crash. In addition, an unexpected position change of the lift axles may increase the risk of injury.
- Remedy
- Dealers will update the VCU software, free of charge. Owner letters were mailed August 19, 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 number for this recall is 25PACF.
Recall number 25V436000 · Recall details
Technical service bulletins for the 2026 Peterbilt 579 58
Bulletins tell dealers how to fix known problems. A warranty extension means the manufacturer pays for that repair for longer.
- The new 2.1m day cab lift tools, a Level 3 mandatory tool, are now available to order.
- There is an update to the CARB Base Emissions Warranty Limits table and Manufacturer’s Warranty Coverage...
- Eaton service bulletin TAIB-1026 instructs dealers to update the master switch module (MSM) software
- The campaign expiration date has been extended from 01/01/2027 to 06/01/2027.
- Certain chassis with Cummins X15N engines require updated engine harness relays due to the risk of water...
- Additional chassis have been added to the population
- Updated parts table with new dielectric grease.
- Certain chassis with CARB 2024 compliant MX-13 engines must have the PEU wiring harnesses updated
- "Kenworth: Dealers should check the chassis list and SIR weekly for VIN changes
- An exhaust manifold slip joint seal kit is now available for EPA 2017-2024 PACCAR MX-13 engines.
What 2026 Peterbilt 579 owners say
Most recent owner complaints, unedited.
Compare the 2026 Peterbilt 579
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Questions about the 2026 Peterbilt 579
Is the 2026 Peterbilt 579 reliable?
Owners have filed 1 complaint about the 2026 Peterbilt 579, fewer than a typical 579 model year.
What is the most common problem with the 2026 Peterbilt 579?
Brakes, with 1 complaint.
How many recalls does the 2026 Peterbilt 579 have?
2 recalls, covering service brakes, air and exterior lighting.
Was there a recall on the 2026 Peterbilt 579 brakes?
Yes, 1 recall: 26V442000. Check your VIN to see if your car still needs the free repair.
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