2023 Peterbilt 389 Spark Plug Type & Gap
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Quick reference
| Engine | OEM Plug PN | Aftermarket (NGK/Denso/Motorcraft/ACDelco) | Gap (in/mm) | Torque (lb-ft / Nm) | Interval |
|---|---|---|---|---|---|
| Paccar MX-13 | N/A (Diesel) | N/A (Diesel) | N/A (Diesel) | N/A (Diesel) | N/A (Diesel) |
| Cummins X15 | N/A (Diesel) | N/A (Diesel) | N/A (Diesel) | N/A (Diesel) | N/A (Diesel) |
Why the right plug matters
For the 2023 Peterbilt 389, it's critical to understand that this heavy-duty truck does not use spark plugs. The Peterbilt 389 is exclusively equipped with diesel engines, specifically the Paccar MX-13 and the Cummins X15. Diesel engines operate on compression ignition, meaning they ignite the fuel-air mixture solely through the heat generated by compressing the air in the cylinder, rather than relying on an electrical spark from a spark plug.
Therefore, discussions about spark plug heat range, electrode materials (iridium vs. platinum vs. copper), and gapping procedures are not applicable to the 2023 Peterbilt 389. The components responsible for ignition in a diesel engine are glow plugs (to aid cold starting) and fuel injectors (to deliver and atomize the fuel).
How to gap a spark plug
This section is not applicable to the 2023 Peterbilt 389 as it utilizes diesel engines which do not have spark plugs.
Replacement procedure tips
This section is not applicable to the 2023 Peterbilt 389 as it utilizes diesel engines and therefore does not involve spark plug replacement.
Known issues
As the Peterbilt 389 uses diesel engines, issues such as cracked porcelain on Ford 3-valve spark plugs or broken plug shells are not relevant. Diesel engines have their own set of specific maintenance considerations, primarily related to fuel system components, turbochargers, and emissions systems.
Need plugs replaced? Find a shop on Repairius.
More specs for the 2023 Peterbilt 389
Oil Capacity & Filter
Capacity, weight, filter PN, drain plug torque, change interval.
Fluid Type Specs
Engine oil, coolant, ATF, diff, brake, PS, DEF — with OEM spec numbers.
Coolant Capacity & Type
Total system capacity, OEM coolant spec, flush interval, bleed tips.
Transmission Fluid & Service
Trans model, fluid spec, capacity, filter PN, service interval.
Torque Specifications
Lug nuts, drain plug, caliper, axle nut, plug, key fasteners.
Brake Pad & Rotor Specs
Pad PNs, rotor size, min thickness, caliper torque.
Tire Size & Pressure
OEM size, cold psi, bolt pattern, wheel size, TPMS.
Battery Size & Group
Group size, CCA, AGM/flooded, dimensions, reset note.
A/C Refrigerant & Oil
R-134a or R-1234yf, charge oz, PAG oil spec.
Bulb Sizes (Headlight, Tail, Fog)
Headlight, fog, tail, turn, reverse, interior.
Factory Maintenance Schedule
Service intervals by mileage, severe-duty notes, known issues.
Towing Capacity & Payload
Max tow, payload, GVWR/GCWR, hitch class by trim.
Fuse Box Diagram & Amperage
Fuse box locations, layout, amps, and what each fuse controls.
Serpentine Belt Routing & Length
Belt routing, length, rib count, OEM + aftermarket PNs.
Wheel Alignment Specifications
Camber, caster, toe ranges (front & rear), adjustability notes.
Paint Color Codes
All factory colors with paint codes, sticker location, touch-up tips.
Wiper Blade Sizes
Driver/passenger/rear blade size, attachment, OEM + cross-refs.
Transmission & Axle Gear Ratios
Trans gear ratios, axle ratios, RPO codes, tow vs MPG impact.
Key Fob Programming
DIY programming steps, FCC ID, fob PN, battery, transponder.
Same spec — other model years
Maintenance & repair guides
2023 Peterbilt 389 Maintenance Schedule →
Available maintenance guidance; confirm the manufacturer schedule.
Repair planning references →
Plan the scope of work; detailed procedures need configuration-matched evidence.
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Values can vary by engine, trim and build date; check your VIN-specific service information. Updated 2026-06-24.