2020-2023 Chevy Duramax L5P Parts & Upgrades

The L5P Duramax in the 2020-2023 Silverado HD

GM redesigned the heavy-duty Silverado for 2020 and left the engine where it was. You still have the 90-degree 6.6L V8 with a deep-skirt iron block, aluminum heads, Denso common-rail injection to 29,000 psi and a single BorgWarner variable-geometry turbo that also works as the exhaust brake. Behind it, the Allison 1000 six-speed gave way to the GM-built 10L1000 ten-speed, and the frame, cooling stack, prop shaft, rear axles, airbox and exhaust routing all changed with the truck. That split is the most useful thing to know before you order. Long-block parts, heads, pistons and valvetrain are shared with 2017-2019, but they are not shared with 2024 and later, which got new pistons, heads, head gasket, valve springs and fuel rails. Service parts went the other way: the oil filter changed at 2020 to PF26, now superseded to PF63B, the air filter changed to A3248C and the belts changed, while the TP1015 fuel-filter cartridge stayed the same part from 2017 through the current trucks. The rest of our Duramax catalog covers the parts that span generations.

What fails and why

On these trucks the documented trouble is transmission, sensor and electrical work rather than the rotating assembly.

• Torque-converter clutch shudder in the ten-speed is the most reported complaint: a rumble-strip vibration at light to moderate throttle and steady speed, worse when warm and under load. GM issued TCM calibration guidance for certain 2020 trucks.
• Heat is the other transmission theme. Twisted or kinked factory cooler lines are documented on these HD trucks causing harsh shifts, surge, shudder and elevated fluid temperature, a thermal bypass valve stuck closed blocks cooler flow, and sustained towing near the top of the GCWR can push fluid temperature into a warning and a derate.
• The MAP sensor soots up from EGR flow and reports the wrong manifold pressure, which feels like a misfire, rough idle, hesitation or low power and usually sets a check-engine light.
• P0204, P020D and P0300 with limp mode are usually the number four injector connector, not the injector itself.
• Lazy spool, boost that does not match command and a weak exhaust brake are the most consistently reported turbo complaints, but charge-air leaks at the intercooler boots and plain intake restriction imitate all three. A leak feels worst in heat, and the truck feels normal on a cool morning.
• A packed cooling stack, meaning bugs and debris between the intercooler, condenser and radiator, makes the truck feel soft under load and run hotter, which feeds straight back into transmission temperature.
• Idler and pitman arm play lets the center link move, which shows up as highway wander and uneven tire wear, and it accelerates after a lift or a tire upsize.

Stock replacement vs. upgrade

Most of what we install on a 2020-2023 Silverado HD is maintenance-grade and should stay that way: OE-type oil and fuel filters on schedule with the water-in-fuel drain exercised, DEXRON ULV in the ten-speed and nothing else, OE-size rotors and pads in the factory 355 and 360 mm dimensions, thermostats and upper and lower hoses done with the first coolant change. Upgrade where the factory margin is thin. For heavy towing that means a deep aluminum pan with a magnetic drain and a temperature port, an auxiliary cooler, a cooler-line inspection, and fluid and filter at 30,000 to 45,000 miles instead of the longer factory interval. Past roughly 500 hp, or after a tire upsize with no regear, the stock converter clutch and stator become the limit, which is where billet multi-disc converters and reinforced valve bodies come in. On the air side the compliant path is a CARB EO-numbered intake such as the Banks Ram-Air and a DPF-back exhaust that leaves the DOC, DPF and SCR exactly as GM built them; the measured benefit is far less backpressure at the DPF and a side-exit tip that keeps regeneration heat, which can reach about 1,100 degrees at the tailpipe, off a trailer tongue. For power, the factory E41 ECM is locked, so the Banks Derringer High Output with its CARB Executive Order is the straightforward 50-state option, and its TransCommand logic looks after the ten-speed. Raising engine output without a transmission calibration can trip the TCM's torque monitoring into limp mode.

What we carry

Hard parts for this platform come mostly from Wehrli Custom Fabrication and PPE: thermostat housings, upper coolant pipe kits, up-pipe bolt and turbo gasket kits, billet exhaust manifold and up-pipe kits, oversized oil filters and filter sockets, forged tie rods and drilled steering assembly kits. BDS Suspension covers heavy-duty tie rod kits and lift hardware, BD Diesel and Mishimoto the turbo accessories and cooling side, and Alliant Power with ACDelco the OE-grade service items, including glow plugs, oil filters and coated rear rotors for duallys. MBRP mufflers and resonators sit in the exhaust group, B&W Trailer Hitches and Big Hitch Products in hitches, Air Lift for air springs, FASS for water-separator filtration, and Hot Shot's Secret with Lucas Oil for CK-4 engine oil, coolant and fuel additives. Edge Products and HP Tuners supply monitors, EGT kits, pressure sensors and A-pillar mounts, and Fleece Performance Engineering, Merchant Automotive, Banks Power and Calibrated Power fill in coolant plates, HP4 pump gasket kits, turbo inlet elbows and drop-in turbos. Brake, steering and shop-tool items round out the shelf.

Fitment notes

Order by cab, bed, drivetrain and rear-axle type. The 2500HD uses an AAM 11.5-inch rear ring gear and the 3500HD a 12.0-inch, so gears, carriers and covers split by model and RPO. Rear rotors differ between single-rear-wheel trucks at 360 by 34 mm and duallys at 355 by 40 mm in the same model year. Wheels are 8x180 on the 2500HD and the 3500HD SRW and 8x210 on the dually, and 8x180 does not cross with pre-2011 8x165.1 wheels. Exhaust is the strictest fit on the truck: routing changed with the 2020 frame, so 2017-2019 DPF-back systems do not fit, and the five-inch Banks Monster covers double cab and crew cab short and long beds only, not regular cab, not dually, and not 2023.5 and later trucks built with dual MAP sensors. Intakes and panel filters changed with the 2020 airbox as well, and the year ranges are not uniform: Banks lists its 2020-2023 Ram-Air as not fitting 2024 and up, while S&B lists one kit through 2026, so verify the specific part instead of the pattern. Thermostats changed for 2020. The WCFab aluminum upper coolant pipe kit is built around the OEM radiator. Puck-system gooseneck hardware needs the factory fifth-wheel and gooseneck prep package; without the pucks in the bed you need a frame-mounted rail kit. When in doubt, verify by VIN.

Frequently asked questions

Is the 2020-2023 L5P the same engine as 2017-2019?

Yes. Every 2020-2023 truck is rated 445 hp at 2,800 rpm and 910 lb-ft at 1,600 rpm, the same as 2017-2019, and the long block is shared. The 2020 jump in capability came from the ten-speed, the cooling package, the axles and the frame, not from the engine. The 2024 refresh is the one that changed it, to 470 hp and 975 lb-ft with different pistons, heads, injectors and fuel rails.

Does my Silverado HD have a CP4 pump?

No. The L5P uses a three-plunger Denso HP4 high-pressure pump fed by an in-tank electric lift pump at 55 to 60 psi. The Bosch CP4.2 belongs to the 2011-2016 LML, and some vendor articles still get this wrong. Anything written about CP4 failure or CP3 conversions does not apply to your truck. The real risk to any common-rail pump here is water and dirt in the fuel.

What causes the vibration I feel at steady highway speed?

The usual answer on this platform is torque-converter clutch shudder in the 10L1000, which feels like rumble strips at light to moderate throttle and gets worse once the truck is warm. Before anything expensive we check fluid condition and level, look for twisted or kinked cooler lines and watch how trans temperature behaves, because restricted cooler flow and a stuck thermal bypass valve produce the same complaints. Larger tires without a regear add converter load too.

Will a 2017-2019 exhaust or intake bolt on?

No. The 2020 frame changed exhaust routing, so a 2017-2019 DPF-back system will not fit, and the airbox and panel filter changed as well, so intake kits and filters are not interchangeable. Transmission parts are a hard no in both directions: the 10L1000 shares nothing with the Allison 1000, and plenty of pans, filters and converters sold as Allison parts online are for the older six-speed.

Which oil and fuel filters does a 2020-2023 truck take?

The oil filter changed with the 2020 truck to PF26, since superseded to PF63B, so either number points at the same current part. Capacity is 10 quarts with the filter, on 15W-40 CK-4 or 5W-40 below zero degrees. The fuel filter did not change: the TP1015 cartridge in the frame-rail housing covers 2017 through the current trucks. Exercise the water-in-fuel drain every time you change it.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.