Quick Answer: An L5P CAN Bus plug is an electrical component used to address specific NOx and DEF module connections on a properly configured off-road or competition-use 6.6L Duramax. The 2017–2019 L5P commonly uses four plugs, while the 2020–2023 layout commonly uses three.
The most important buying detail is the model year. A plug kit made for a 2017–2019 Silverado or Sierra should not be assumed to match a 2020–2023 truck, even though both use the L5P engine.
What Is an L5P CAN Bus Plug?
CAN stands for Controller Area Network. It allows the ECM and other control modules in the truck to exchange data over a shared communication network.
On an L5P Duramax, the NOx and DEF modules are connected to this network. When those modules are removed from a legally permitted off-road or competition-only truck, compatible CAN Bus plugs may be used to address the related vehicle-side connections.
The plugs can also provide a cleaner, sealed connection instead of leaving factory harness ends exposed to water, mud, salt, and gravel dust.
What an L5P CAN Bus Plug Does Not Do
A CAN Bus plug does not add horsepower, change fuel delivery, unlock the ECM, or replace compatible calibration.
Think of it as one electrical part of a complete off-road L5P delete system. Exhaust hardware changes the physical layout, calibration controls how the ECM operates, and the CAN Bus plugs address specific module connections.
For owners comparing a broader off-road parts path, an EGR, DPF, downpipe and CAN Bus plug L5P all-in-one kit can make more sense than buying each major component separately, as long as the truck’s model year, tuning path, and legal use case are confirmed first.
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Which Trucks Are Covered?
The available configurations cover the following 6.6L L5P Duramax trucks:
- 2017–2023 Chevrolet Silverado 2500HD
- 2017–2023 Chevrolet Silverado 3500HD
- 2017–2023 GMC Sierra 2500HD
- 2017–2023 GMC Sierra 3500HD
SPETUNER offers separate model-year options for the 2017–2023 L5P CAN Bus Plug Kit. Select the truck’s exact model-year group before ordering.
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2017–2019 vs. 2020–2023 L5P CAN Bus Plugs
| Detail | 2017–2019 L5P | 2020–2023 L5P |
|---|---|---|
| Typical total plug count | 4 | 3 |
| Typical NOx connections | 3 | 2 |
| Typical DEF connection | 1 large plug | 1 large plug |
| Work areas | Engine bay and multiple frame locations | Engine bay and underbody harness |
| Main installation challenge | Finding all four connections | Identifying the revised harness layout |
| Estimated installation time | 45–90 minutes | 30–75 minutes |
The number of plugs is not the only difference. Connector design, module placement, harness routing, and mounting points may also change between the two model-year groups.
Where Are the L5P CAN Bus Plugs Located?
The L5P connections are not grouped in one place. Depending on the model year, one connection is in the engine bay and the remaining connections are positioned along the frame or underbody harness.
2017–2019 location overview
The earlier layout commonly includes:
- Plug 1 in the rear corner of the engine bay
- A large DEF connection inside the front passenger-side frame
- A NOx connection outside the frame near the front driver-side wheel
- A NOx connection inside the frame behind the rear passenger-side wheel
For exact pictures and installation steps, use the 2017–2019 L5P CAN Bus plug location and install guide.
2020–2023 location overview
The newer layout commonly includes:
- One connection near the upper engine wiring and firewall
- One underbody NOx connection along the frame harness
- One larger DEF-related connection
See the revised layout in the 2020–2023 L5P CAN Bus plug location and install guide.
How to Identify a NOx Sensor and NOx Module
The metal NOx sensor threads into the exhaust stream. Its wire leads to a separate electronic module, which then connects to the vehicle-side harness.
When a connection is difficult to find, start at the sensor and follow its wiring. This is more reliable than searching the frame by sight alone.
Explore 2017+ L5P Duramax Upgrades
Working on a 2017–2023 Chevy Silverado or GMC Sierra 6.6L L5P Duramax? Explore vehicle-specific CAN Bus plugs, tuning interfaces, delete hardware, CCV reroute kits, downpipes, and other upgrade options for lawful off-road or competition builds. Always check the model year, cab configuration, and product fitment before ordering.
Why Owners Buy the Wrong Plug Kit
- They shop by engine name without checking the model year.
- They assume every L5P uses four plugs.
- They confuse a simple dust cap with an electrically configured CAN Bus plug.
- They compare connector color instead of terminal layout and locating keys.
- They start disassembly before comparing the truck’s connectors with the kit.
Lay the plugs out before starting. Separate the smaller NOx plugs from the larger DEF plug and confirm the expected quantity for the truck’s model year.
Does Every L5P Need CAN Bus Plugs?
No. A stock, emissions-intact truck should retain its functioning factory modules and connections.
These plugs are relevant only to specific legally permitted off-road, competition, closed-course, or export configurations. Whether they are required depends on the hardware, calibration, model year, and instructions supplied for that build.
Can a CAN Bus Plug Fix U-Codes?
A correctly matched and installed plug can address the intended module connection, but it will not repair damaged wiring, low battery voltage, corroded terminals, or an incompatible L5P calibration path.
If the truck shows U-codes after installation, check:
- Correct kit for the model year
- Correct plug at each connection
- Fully seated primary and secondary locks
- Bent or pushed-back terminals
- Water or corrosion inside the connector
- Both batteries and cable connections
- Compatibility between hardware and calibration
How Difficult Is the Installation?
The physical job is about 3 out of 5 in difficulty. Connecting a matched plug is simple; finding the correct vehicle-side connectors is the harder part.
You may need to work in the engine bay and underneath the truck. Heavy dirt, corrosion, broken locks, and previous wiring work can make the job take longer.
Before You Order
- Confirm the truck is a 2017–2023 6.6L L5P Duramax.
- Record the exact model year.
- Check whether the truck belongs to the 2017–2019 or 2020–2023 group.
- Compare the expected plug count with the kit contents.
- Review the year-specific installation guide.
- Confirm the legal use case before modifying factory emissions equipment.
Related L5P Duramax Guides
- What Do You Need for an L5P Duramax Off-Road Build?
- Best Tuner for L5P Duramax
- Complete L5P Duramax Regen Guide
Legal and Use Notice
CAN Bus plugs used with the removal or bypass of DPF, DEF, SCR, NOx, EGR, or other emissions equipment are intended only for off-road, closed-course, competition, export, or other legally permitted applications.
Removing or disabling factory emissions equipment is not legal for public-road vehicles in many jurisdictions. Street-driven trucks should retain functioning factory emissions equipment.
FAQ: L5P CAN Bus Plugs
Q: How many CAN Bus plugs does an L5P use?
A: A 2017–2019 L5P commonly uses four plugs, while a 2020–2023 truck commonly uses three. Confirm the kit instructions before installation.
Q: Are all L5P CAN Bus plug kits the same?
A: No. Plug quantity, connector design, terminal layout, and module placement can differ between model-year groups.
Q: Do L5P CAN Bus plugs add horsepower?
A: No. They address electrical connections and do not create additional engine power.
Q: Can a CAN Bus plug replace tuning?
A: No. A CAN Bus plug does not unlock or recalibrate the ECM.
Q: Where is the first L5P CAN Bus connection?
A: Both model-year groups commonly have a connection in the rear or upper area of the engine bay. Its exact position differs between the earlier and later layouts.
Q: Should I disconnect both batteries?
A: Yes. The L5P uses a dual-battery system. Both negative terminals should be disconnected before opening module connections.
Q: What should I do if a plug does not fit?
A: Stop and verify the year, connector shape, locating keys, terminal count, and intended location. Do not cut or modify the connector.
Lars
Diesel Performance Engineer | 15+ Years Experience
"Empower Your Beast: Run Cooler, Pull Harder, Last Longer."
