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Turbocharger Troubleshooting: Resolving Intermittent Boost Issues on a L5P

Understanding Boost Issues in 2017-2019 L5P Trucks

Owners of the 2017-2019 L5P may sometimes face intermittent boost issues, which can affect the truck's performance. This guide aims to assist in identifying and fixing these problems, focusing on the key diagnostic trouble codes (DTCs): P003A, P0046, and P2599.

Deciphering Turbocharger DTCs

- P003A: Points to a learning issue in the turbocharger's boost control system.

- P0046: Suggests a fault within the boost pressure output circuit.

- P2599: Indicates the turbocharger vanes are positioned higher than normal, and will set alongside of P0046.

L5P P003A, P0046, P2599

Initial Inspection and Checks

Starting with a thorough visual inspection is essential to rule out any straightforward mechanical issues. Checking the battery's condition and ensuring all connections are secure is also crucial, as low voltage can trigger these codes mistakenly. Any debris around the linkage can also cause these codes. Check fuses. SCRPM/ SEN ENB 10A supplies power to the Turbo Actuator, but if this fuse is blown, the truck will have other codes related to NOx Sensor 1, Reductant Control Module, and other emission system related codes.

Assessing the Turbocharger Actuator

A quick test you can perform is to cycle the ignition and observe the actuator's behavior during its self-learning and cleaning cycles. When the ignition key is turned to the off position, the turbocharger actuator will sweep the vanes 3 times. Once to learn, twice to clean. An actuator that doesn't perform these functions might need further inspection or replacement.

Checking Linkage and Actuator Health

Inspect the VGT connector and linkage for any debris or loose connections. After turning the key off, and allowing the truck to power down, the actuator arm should move freely by hand from the vertical position down to the horizontal position, and then return back to the vertical position on its own.

Further Diagnostic Steps

If the arm/linkage is stuck, or you feel any binding, disconnecting it from the actuator for a closer inspection is the next step. Remove the ball stud using a H4 Hex head socket. Repeat the key off test. A non-responsive actuator after these checks usually requires replacement. While the linkage is disconnected, you can check the linkage and the vanes by moving the linkage up and down. It should move freely with no binding. If the linkage does not move freely, it may be time for a turbocharger.

Using Diagnostic Tools for Clarity

For a more in-depth analysis, use an advanced diagnostic scan tool to check the Turbocharger Vane Position Parameter while controlling the actuator from 10%-90% while also visually checking for movement. If there is no movement, suspect the actuator.

Torque Values:

- Turbocharger Actuator Lever Nut (Ball Stud): 93 in. lbs.

- Actuator Nuts (x4): 119 in. lbs.

Required Tools:

The necessary tools for this job include:

- 10mm socket

- H4 Hex Head Socket

- Inch-pound torque wrench

- Ratchet

Streamlining the Repair Process

The goal is to conduct the diagnostic and repair process efficiently, ideally within an hour, to minimize downtime and restore turbocharger functionality.

Detailed Removal and Installation Process

1. Locating the Actuator: Situated at the top center of the engine.

L5P Actuator

2. Disconnecting the Actuator: Carefully remove the connector to prevent damage.

L5P Actuator Connector

3. Linkage Disassembly: Remove the ball stud with an H4 Hex Head Socket, ensuring the nut doesn't get lost. Pro tip: use tape to hold the nut in place. Just be sure to not push it out while removing the ball stud.

Backside of L5P turbocharger actuator with legend

L5P Turbocharger actuator tape trick

4. Removing the Actuator: Unbolt the four 10mm nuts. Be sure to not drop them. If you drop them, it is unlikely you will recover them. You may need to rotate the actuator to get it in a position to be removed. you will also need to move the actuator arm to clear the bracket.

L5P Turbocharger Actuator Removal


Installation of the new actuator is simple. Just read these instruction backwards. After installation, you will need to perform a Turbocharger Actuator Relearn using an advanced scan tool.

Conclusion: Restoring Your 2017-2019 L5P's Performance

By following this guide, you can systematically address and resolve turbocharger boost issues in your 2017-2019 L5P truck, ensuring it runs smoothly and efficiently. This practical approach is designed to provide clarity and solutions to truck owners and technicians alike.

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