What Causes P0087 Duramax Code [+ Easy Solutions]

There are 02 types of fuel pressure in a Duramax low fuel rail pressure and high fuel rail pressure.

Both of them are not normal fuel pressure.

They cause various problems to your vehicle.

Code P0087 appears on your vehicle due to low fuel rail pressure.

Low fuel rail pressure means your engine is not getting the fuel supply that it should.

Code P0087 is a very common question I get, and it is actually a pretty loaded question.

However, there are a lot of common things like Limp Mode or Reduced Engine Power Mode that are associated with this code.

Today, I will explain must know info about this code.

What is P0087 Code?

Duramax ECM code P0087 means low fuel rail pressure.

It occurs when the fuel supply to the injector is lesser than standard.

It means the oil supply to the injectors is lesser than it should be.

The vehicle will automatically go to Limp Mode when this problem occurs because of the lean fuel condition.

All Causes and Solutions of Code P0087 Duramax

There are 07 causes of Duramax P0087 code to pop up in the OBD scanner.

Let’s discuss these causes with solutions shortly.

Note: These causes and solutions are applicable for all Diesel engines, including Duramax LBZ, LB7, LML, LMM, and LLY.

1. Faulty Fuel Pump

Faulty Fuel Pump

Unlike the petrol engine, diesel doesn’t have spark plugs in the fuel injectors.

Instead, the Duramax diesel engine uses a high-pressure fuel pump to spray fuel into the combustion chamber.

That is why the fuel pump is also known as the heart of the diesel engine.

GM used CP4 high-pressure fuel injection pump in their 2011 to 2016 6.6 Duramax diesel vehicles.

It’s reported by many 6.6 Duramax owners and experts that the CP4 Fuel pump has a manufacturing fault.

Almost every CP4 fuel pump often fails while the vehicle is in motion.

GM doesn’t cover the fuel pump in their warranty.

Instead, they blame the fuel contamination.

So, the owners of the Duramax have to bear the expenses by themself.

The replacement cost of a CP4 fuel pump is around $12,000, which is huge.

That is why ‘The Texas Motorist’ became frustrated and filed a lawsuit against General Motors in 2018.

I personally don’t advise you to buy Duramax 2011-2016 models.

You will be a sufferer if you do so.


As I have mentioned, GM doesn’t cover up the warranty by blaming fuel contamination. You have to replace the CP4 fuel pump with a new one.

Read also Duramax CP3 pump failure symptoms.

2. Contaminated Fuel

Contaminated Fuel

All Duramax 6.6L V-8 engines use Ultra low sulfur diesel and B20 bio-diesel.

GM claims most C4 fuel pump failure is due to contaminated fuel diesel.

There are three types of diesel fuel contamination.

01. Water contamination

02. Inorganic debris like dust, sand, rust, etc.

03. Organic debris, including fuel breakdown, waste fuel, microbial contamination, etc.

There are 03 most common signs of contaminated diesel black smoke from the exhaust system, rotten-smelling fuel, and discolored fuel.


If you see any of these signs, you must find a trustworthy gas station.

Apply fuel additive cleaner to the fuel tank. It will clean the diesel and make your fuel contamination free.

3. Blockage in the Supply Oil Line

Blockage in the Supply Oil Line

There is a fuel supply line from the fuel tank to the injection pump in every vehicle, including all Duramax.

The fuel supply line goes to the engine’s injector from the fuel tank.

Sometimes the fuel rail bends and becomes soft in some specific areas.

The fuel supply becomes less than it should be due to these bends and soft spots and causes P0087 code in your Duramax.


Don’t try to solve this issue by fixing the fuel supply line because it won’t work.

Instead, change the whole fuel supply rail.

4. A Small Leak in the Oil Supply Line

Sometimes there are small leakages in the fuel supply line, which causes the P0087 code in your vehicle.

So, you must inspect visually if there is a leakage in the fuel line or not.


Don’t try to cover up the leakage; instead, install a new fuel supply rail.

5. Debris in the Fuel Rail

When your vehicle gets old, naturally, there will be debris and alien particles in the fuel rail.

Debris and alien particles clogged the fuel rail and caused low oil pressure code P0087 in your vehicle.


Pull the injectors out of the fuel rail and flush them out with the help of a fuel injector cleaning kit.

It will clean the unwanted debris out of the fuel rail.

6. Faulty Fuel Pressure Regulator

Faulty Fuel Pressure Regulator

Duramax has an electronic fuel pressure regulator in most of their models.

The electronic fuel pressure regulator system helps to maintain the standard fuel pressure in the engine’s fuel injection system.

If the sensor detects low fuel pressure in the fuel rail, then the fuel pressure regulator supplies extra fuel to the engine through the injectors.

It also does the vice-versa if needed.

Sometimes, the fuel pressure regulator gets damaged or faulty for various reasons and causes P0087 code in your vehicle.


Remove the faulty fuel pressure regulator and install a new one.

7. Faulty Injectors

Faulty Injectors

The injector of Duramax lasts up to 2,00000 miles.

You don’t need to replace the injector within this period.

The possibility of a faulty injector for P0087 code within this period is very low and highly arguable.

It’s very rare for Duramax users.

However, I can’t ignore the possibility though it’s very low.


Fuel injectors are irreparable.

So, you can’t repair it.

The price of a Duramax injector is around 500 bucks, and the labor cost is around 1200 bucks.

That means replacing the Duramax injector will cost you around 1700 bucks.

What Should I Do If P0087 Code Pops Up in My Car?

It’s challenging to find out the exact reason for the problem.

But you can apply these methods to eradicate P0087 code.

01. First, inspect the fuel rail from the fuel tank to the fuel injector.

If you notice any bends with a soft spot, then be sure the P0087 code pops up for bends or soft spots.

Cause it hinders the fuel supply and causes low fuel rail pressure.

02. If you don’t notice any bends or soft spots on the fuel rail, then flush the fuel rail with cleaner additives.

It will clean out all the alien debris from the fuel rail and solve the P0087 code.

03. If solution numbers 01 and 02 don’t work, then be sure the problem lies within the fuel pump or fuel pressure regulator.

Diagnose them to be 100% sure and replace the culprit one.

Read also the meaning and causes of p2563 duramax.

Related FAQs

How to Get Rid of Duramax P0087 Limp Mode?

Duramax limp mode is also known as Duramax reduced engine power mode.

Duramax limp mode is caused by low fuel rail pressure.

There are 07 reasons that can cause a limp mode on your Duramax.

I have mentioned all the possible causes with solutions at the beginning of this article.

Can ECM Programming Eradicate Code P0087?

As for my personal experience, some owners have done ECM programming to eliminate the P0087 code.

Some claims it worked for them, but some differ.

My personal opinion about ECM programming is positive.

But you have to do the programming before the P0087 code arises on your scanner, not after.

ECM programming alters the fuel rails’ pressure, which will stop the code from appearing before it becomes a problem.

If you are a Duramax 2011-2006 model owner, then ECM programming won’t work.

Because these models use a C4 fuel pump which has the manufacturing faults I mentioned above.

I suggest changing the fuel pump to avoid this code or limp mode.

What are the symptoms of a bad diesel fuel pressure regulator?

A bad diesel fuel pressure regulator shows the following symptoms:

  • Engine misfires
  • Rough idling
  • Engine vibrating or stalling
  • Check engine light illuminated
  • Unusual noises
  • Fuel leaks
  • Black smoke from the exhaust

If you see the symptoms, take your vehicle to a repair shop as soon as possible.

What happens if you drive on a bad fuel pressure regulator?

If you drive on a bad fuel pressure regulator, several problems will occur.

Sometimes it causes severe problems and results in a costly repair.

Some common issues that are caused by driving with a bad fuel pressure regulator are:

  • Reduced engine power
  • Rough idling
  • Acceleration issues
  • Fuel leaks
  • Back firing
  • Poor fuel economy
  • And starting issues

What codes will a bad fuel pump throw?

A faulty fuel pump generally throws the following error codes:

  • P0230 Error Code: The code indicates circuit issues between the PCM and the fuel pump.
  • P0627 Error Code: Fuel pump “A” control circuit/open, when the fuel pump is not working correctly, the powertrain control module triggers the code.
  • P0251: The code indicates an abnormal reading provided by the fuel rail pressure sensor to the PCM.
  • P0148: It is a diagnostic trouble code that indicates “Fuel Delivery Error.” The PCM triggers the error code and detects mismatch between the actual fuel pressure and the specified fuel pressure.

Final Thoughts

As P0087 is a very common code for Duramax owners, you must know all the problems associated with this code.

You can diagnose and apply the solutions I mentioned in this article to eliminate this code.

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