2026 Peterbilt 579 problems, complaints & recalls
Most-reported problem areas: Service Brakes (1)
Safety recalls (2)
Service Brakes, Air:supply:quick Release Valve 2026-07-08 · campaign 26V442000 · 8 vehicles
Defect: 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.
Fix: 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.
Exterior Lighting:lighting Control Module:software 2025-06-26 · campaign 25V436000 · 56,260 vehicles
Defect: 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
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.
Fix: 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.
Service bulletins (57)
Technical service bulletins are repair instructions manufacturers send dealers for known issues. Unlike recalls, the fix is not automatically free — but naming the bulletin at the service desk can save diagnosis time and support goodwill repairs.
Unknown Or Other 2026-10-28 · 99-050 · Service Bulletin/Repair Instructions
there is an update to the carb base emissions warranty limits table and manufacturer’s warranty coverage section in certain engine model year (emy) 2024-2026 px-7 and px-9 operator’s manuals.
Unknown Or Other 2026-10-23 · 12-001 · Service Bulletin/Repair Instructions
the campaign expiration date has been extended from 01/01/2027 to 06/01/2027.
Electrical System 2026-10-23 · 37-007 · Service Bulletin/Repair Instructions
eaton service bulletin taib-1026 instructs dealers to update the master switch module (msm) software. the update must be completed before performing a davie4 learn dash switches procedure to fix intermittent dash switch functionality.
Engine 2026-10-21 · 45-071 · Service Bulletin/Repair Instructions
certain chassis with cummins x15n engines require updated engine harness relays due to the risk of water intrusion.
Electrical System 2026-10-16 · E328 · Service Bulletin/Repair Instructions
updated parts table with new dielectric grease.
Engine 2026-10-16 · E340 · Service Bulletin/Repair Instructions
additional chassis have been added to the population
Showing the 6 most recent of 57 bulletins. Search all of them free at nhtsa.gov.
What owners report
2025-08-22 · Service Brakes · 200 mi“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 stat…”
Excerpts of consumer complaints filed with NHTSA, lightly truncated. They are owner statements, not verified findings.