2020 Peterbilt 579 PACCAR MX-13 — Should You Buy One?
Typical asking price: $80,000–$115,000. There are 2 high-severity known issues you need to know before handing over a check.
Kestrel Take
The 579 is Peterbilt's aerodynamic flagship — fuel-efficient, driver-friendly, and equipped with Peterbilt's SmartNav and optional Bendix ADAS. The MX-13 by 2020 is a mature engine with most early issues resolved. Solid choice for a used long-haul truck with modern features.
What we checked
Not checked against public records
No federal database covers this category in a form we can match to a single year and model. What follows is our own write-up, and it has not been reconciled against an official record. Treat it as a starting point, not a verdict.
Known Issues for the 2020 Peterbilt 579 PACCAR MX-13
Ranked by wallet impact. These are documented, recurring problems — not freak accidents. How we decide that.
DEF, DPF, and SCR system failures trigger derate modes. Pre-purchase ECM scan is mandatory.
Repair cost (estimate): $500-$4,000
Source: not yet checked against public records.
EGR cooler failures on the MX-13 — white smoke and coolant loss are the indicators. By 2020 the cooler design had improved but not eliminated the concern.
Repair cost (estimate): $2,000-$5,000
Source: not yet checked against public records.
Bendix Fusion or OnGuard ADAS requires calibration after windshield replacement. Verify all safety systems active.
Repair cost (estimate): $500-$1,500 to calibrate
Source: not yet checked against public records.
Walk-Away Red Flags
- ✗Active emissions or engine fault codes on ECM scan
- ✗White smoke or coolant loss — EGR cooler
- ✗ADAS warning lights active
Good Signs
- ✓Peterbilt dealer PM service history
- ✓ECM scan clean
- ✓Long-haul highway miles
- ✓EGR cooler replaced or inspected and documented
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Known issues on this page are based on documented owner reports, NHTSA complaints, class-action records, and manufacturer technical service bulletins. Individual vehicles vary. A pre-purchase inspection by a trusted mechanic is always worth doing.
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