3 Most Common L5P Duramax Problems | Expert Opinion and Solution

Although the L5P Duramax is the most reliable post-emissions engine produced to date, you may encounter some issues if you use one.

Injection failure and map failure are the most common problems faced by the users. Have you yet met with them? If you did, you better know about more L5P Duramax problems and their solutions.

In this article, we will try to give you more clarity about L5P Duramax problems, and how you can solve them. We will also discuss the maintenance of L5P engines and of course answer some of the FAQs. 

Duramax L5P Specs And Overview

The L5P is the most recent variant of the Duramax V8 diesel engine. It has a 90-degree V-8 arrangement, which is similar to previous engine designs. 

For further durability, the block is made of cast iron with induction-hardened cylinder walls and five nodular main bearings. L5P Duramax engine’s block feature is also planned with a profound skirt and four-bolt, with cross belted fundamental covers.                                          

Specification chart for L5P Duramax Engine

ProductionSince 2017
Displacement6.6L/403 cu. in.
Horse Power445 hp at 2800 rpm
Torque910 lb-ft at 1600 rpm
Injection PumpDenso H4P(29000 psi)
Bore  103mm
Fuel systemHigh-pressure common-rail
Oil capacity10 qt/9.5L
Emissions ControlsIntake throttle, EGR, SCR

Which Cars Model Has L5P Duramax Engine? 

L5P Duramax is a very efficient and powerful engine for heavy cars. You can find this engine only in Chevrolet Silverado HD and GMC Sierra HD 2017-2022 models. Some specific models are very widely received by customers.

2017 Chevrolet Silverado HD 

The Lord of the Silverados is the 2017 Chevrolet Silverado 3500HD. This standard uncompromising pickup truck has a towing limit of 23,200 pounds, a payload limit of 7,153 pounds, and a force rating of 910 lb-ft. It accompanies two motors: an internal combustion 6.0L V8 and a super diesel 6.6L L5P V8 with 445 drive, which is the most in the class.

2017 GMC Sierra HD

The 2017 model of GMC Sierra is a more improved and impressive version than the previous model. The installation of an L5P Duramax made the 2017 GMC Sierra HD more fast and strong. In the newest editions, the features are not much changed.

The 2020 Silverado 3500 HD

This car is hot as fire! It is the mightiest Silverado ever. The 6.6L L5P Duramax turbo-diesel engine in this car makes  445 hp and 910 lb-ft torque, combined with an all-new Alison 10-speed automatic transmission.

What Are The Signs Of L5P Duramax Issues? 

There are some problems you might face as an L5P Duramax user. Every problem has its own symptoms and solutions. The most common signs of L5P Duramax issues are:

  • Misfiring the engine 
  • The check engine light is on
  • Low performance, and Lack of power
  • Poor performance due to shaky engine
  • The abs and StabiliTrak lights come on
  • Engine stalling, reluctance, and other issues 

3 Most Common L5P Duramax Problems

L5P Duramax is a very new edition of v8 diesel engine. As it is now on the market, it is obvious that there are not many problems you can find about. But here is a list of L5P Duramax problems.

1. Fuel Injector failure

The connector for fuel injector number 4 has been known to blow up from time to time and require replacement. It isn’t with the injector itself, but it can cause vital problems such as fuel injector failure.

What happens?

When the injector fails, your car will enter limp mode and display a P0204, P0300, or P0204 motor code, as well as a P0204 motor code. 

Stabilitrak or ABS lights, failing, unpleasant sitting, shaky motor and generally poor performance are some of the adverse effects to watch out for.


In February 2019, a recall for fuel injector calibration (recall N182179090) was issued. While this recall isn’t specific to the number 4 injector, it’s worth checking if you’ve done it to avoid future injector problems.

  • Replace the stock connector
  • Using a gold-plated connector or LBZ connector will solve the L5P injector failure problem.

2. Sensor Failure on the Duramax L5P (217 MAP)

The problem with the MAP sensor is recorded in L5P engines, and it is actually a very frustrating one too. It is a vital part as it gives the data to the control system on how much fuel needs to be sent into the engine. 

What Happens?

As the engine runs, dust or ashes can block the sensor. And if the map sensor is blocked, it will give random data that are not correct.

Motor slowing down and sometimes motor failures can be faced due to map sensor problems. Overall performance of your engine will be terrifyingly reduced due to this issue.

When this happens, the motor will never function at its best again, and if left ignored, this problem could lead to disastrous motor failure.


Replacing a faulty MAP sensor will cause the clock to reset, which may be a pointless problem. Simply make it a point to clean it regularly, and you will not have this problem.

  • To avoid this problem, it should be cleaned regularly. 
  • If you are having symptoms, check it as soon as possible. Maybe it can be fixed.
  • Delaying can cause a full replacement.

3. Allison 1000 Power Transmission Issues

This cannot be considered a true fault with this engine. Transmission  fights to the extent of making changes for ‘additional strength.

What Happens?

Usually, the factory transmission isn’t designed to handle more than 500 horsepower, so if you want to push it over 600hp, you’ll have to make a few pricey alterations to the transmission. 

Making alternative modifications that work out less expensive in the long run is one technique for avoiding transmission redesigns.


  • Use Pressure-driven overhauls
  • A multi-circle force converter will ease your work
  • A transmission cooler, as well as improved grinding materials, will help the transmission hold up better under the increased stress.

Any problem that causes your truck to go limp should be investigated straight away.

Also read our guide on- 2.8 Duramax Problems

L5P Duramax Maintenance Guide

As you know, the maintenance of a car is the most important factor that decides your car’s performance. It is always the best idea to read the maintenance guide that you got with the engine.

But if you want to maintain your L5P engine by yourself, you should follow the following steps:

  • Change the Engine Oil every 12000 kilometers of service
  • Change the Oil Filter approximately after 12000 kilometers of traveling.
  • Service the Air Filter every 4 years
  • Flush the cooling system after 240000 kilometers of driving
  • Change the External Transmission Filter after 72000 Kilometers of service


In this article, we covered L5P Duramax engine performance, problems, solutions, engine maintenance, and also some needy topics that might prove helpful to you. Here we are answering some of the most commonly asked questions about L5P Duramax. Look out, it can be the question of your mind.

Is The L5P Duramax A Good Engine?

L5P Duramax doesn’t have the CP4.2 The wall, cylinders, and many internal parts are effectively modified. Problems like crankshaft are solved, and not many problems are recorded. So the L5P Duramax is a really good engine.

How Many Miles Will An L5P Duramax Last?

L5P clears approximately 350000-mile mark easily. With proper maintenance, many drivers claim to have 400000 to 500000 miles without any kind of issues.

How Much Hp Can An L5P Handle?

In 2020, GM wanted to know how much hp actually this L5P Duramax can handle. The engine made 1004 horsepower and 1383 lb-ft torque. But for the official record, it is rated 445 hp at 2800 rpm and 910 lb-ft of torque at 1600 rpm from the factory.


L5P Duramax engine users are usually very happy customers. The engine mostly covered all the flaws Duramax had in past years. The ultimate power makes the engine perfect for trucks. 

And now you know how to handle an L5P Duramax engine. So if there’s any problem that pops up you can check it and solve it by yourself. Maybe every time you don’t need to go to the mechanic.

Cars with L5P Duramax are often well-styled, and their performance is pretty satisfying. So if you like fast trucks with fewer problems and have work like transferring heavy items, the L5P Duramax engine might be the right choice.

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