Volvo D12 Engine Problems – How To Diagnose And Fix Them?

Engine malfunction can cause drivers to struggle because it will stop every operation of the car accessories. What are the Volvo D12 engine problems? This post will lead you through all causes and solutions for each issue in detail. Let’s follow us to find out the answer.

What Is a Volvo D12 Engine?

Volvo is known as one of the famous heavy-duty trucks manufactured in Sweden. Volvo D12 engine horsepower is around 400-500. Not only does it feature extremely low emissions, but it also makes maneuvering easier for drivers.

Volvo D12 Engine Problems

What Are Volvo D12 Engine Problems? What Are The Causes?

Volvo D12 engine problems include improperly working engine and engine stopping working. They may come from the idling, turbo, or coolant system fault. Besides, battery, alternator, wiring, and fuel system malfunction may cause these problems.

Engine Not Working Properly

Idling Problem

When the engine is operating, you may notice the idle mode is unstable, the car runs on gas, or the engine heats up quickly. Sometimes, there is a serious case, such as a reverse explosion.

When the ignition system generates sparks too late compared to when the engine needs it, it will often bring about phenomena such as high engine temperature and an explosion in the exhaust pipe because the gasoline is not fully burned. 

Since it is not burned in time, the engine will be flooded with gasoline, making the car not accelerate and damaging the engine.

Turbo Problem

The bearings and valves, input and output supportive components, charge pipelines, and control components of your truck’s turbo are likely the sources of your engine failures.

Slow throttle response is the most common sign on turbocharged engines. This situation occurs when the vehicle has a problem with the fuel system.

Also, when the amount of smoke is too much, even when the engine has warmed up, it could be a sign of a damaged turbo, specifically a crack in the housing or worn seals.

It triggers fuel to leak into the exhaust system, greatly increasing the smoke from the vehicle’s exhaust. Regular blue smoke can signify a worn valve seal or piston ring.

Coolant System Problem

A leaking cooling system is the next most prevalent error in Volvo D12 engines. In most cases, air entering the cooling system can end up with engine overheating.

Coolant leaks through the hole, giving the air a gap to be drawn in. When the air enters, it creates “bubbles” that prevent coolant from reaching the engine and eventually cause overheating.

In addition, condensate coolant also explains why the engine operates abnormally. This phenomenon usually takes place in the winter when the temperature drops, condensing the cooling liquid.

Using poor-quality coolant equals easy freezing and clogs. When it happens, the engine will not be cooled properly and will overheat, wreaking havoc on the radiator and shortening the Volvo D12 engine life.

Engine Stop Working

Battery Malfunction

The management and consumption units on any Volvo car are powered by a battery. The battery needs to work well to turn on a Volvo engine. A bad charger is the reason why you can’t turn on the ignition. 

It is crucial to remember that a vehicle’s battery or charging capacity will reduce over time. Eventually, it will not be able to provide enough power to run the car. Any battery has a certain shelf life. Most of the time, the battery’s manufacturers say that the maximum lifespan of a car battery is 5 years.

Alternator Malfunction

Generator failure due to short-circuit or damage related to other accessories will stop the engine. It provides energy for the car engine to run. If the alternator has a problem, the most obvious signs are a dead battery or the battery warning light flashing/flashing continuously.

In addition, whenever you find it difficult to start the engine, then your generator is definitely having a problem. If you don’t address it soon, your engine will quickly cease working.

Ignition Faulty

Although the ignition switch is not part of the engine, it is clear that the engine cannot start if the switch is damaged. Even when your Volvo uses an ignition or push-button key, you should check once the engine won’t start.

The problem can stem from a broken key or a damaged lock due to a broken circuit. Also, if your Volvo key fob has not been programmed or cleared, it will not receive a signal, and the engine will not run.

Broken Wiring

After performing for a long time, Volvo’s wiring can be broken owing to strong impacts. It can also be corroded by dirt and water. A telltale sign that the wiring has a problem is that the dashboard lights up, but the engine isn’t working.

Fuel Problems

If you do not supply enough fuel, the engine will not work. The cause also comes from the filter, relay, or fuel pump being too old and clogged.

When your car is moving at a slow speed, the fuel pump will take a small amount of gasoline to cool it and add some air. And the fuel pump will overheat and damage the fuel system as a result. It will eventually prevent the engine from working.

How To Deal With Volvo D12 Engine Problems

How To Deal With Volvo D12 Engine Problems?

Regularly Check Car Parts

You should regularly fully charge the battery and avoid letting it completely depleted. A draining battery may be to blame for the car halting while driving, endangering you and those around. Also, turn off unnecessary devices such as radios or A/C if the weather is not too harsh.

Regularly check for warning lights on dashboards. Having them flicker or light up all the time signifies that you should check specific parts for timely repair.

If the fuel warning light comes on, you need to fill up your car immediately with gas. When the coolant leaks or needs to be replaced, you can do it yourself. Choosing the right coolant for your Volvo D12 engine will be the best.

Visit Dealer

You can visit the auto dealer or car service center to check whether the engine or other parts have problems. You can refer to the Volvo service web to get the exact locations. 

If the idling, turbo, battery, or wiring system is broken, it is best to ask the mechanics to fix it. Although there will be a fee, full service will be guaranteed.

Volvo D12 Fuel Pressure Problem – How To Fix?

One of the problems that the Volvo D12 often faces is fuel pressure, apart from the engine-related issues. Malfunctions in the fuel pressure regulator, pump, and injectors are the recipe for this problem.

Regulator Malfunction

Your engine needs to produce energy when you begin to drive constantly. It may quickly lose energy, your car may stall out, or it may abruptly slow down if one or two car’s cylinders are not producing enough power or are moving more slowly than the others.

This is a malfunction that is typically brought on by erratic fuel pressure. This anomaly suggests that your fuel pressure regulator is broken.

It’s difficult to determine whether the regulator is to blame for all of the malfunctions and other problems you are seeing. You should check the fuel pressure first to verify, and a pressure gauge is necessary for it. 

First, turn the ignition switch while the pressure gauge is connected to the valve to check if the reading is in the acceptable range for your Volvo fuel pressure. 

Next, turn off the car to see whether the fuel pressure remains the same or decreases. You can disconnect the battery to reset the fuel gauge to solve the problem if the tool doesn’t show any readings.

If the fuel pressure begins to drop, the regulator will not operate properly, and there is a leak in the fuel system. In this case, the fuel pressure regulator should be completely replaced. 

How to fix Volvo D12 engine problems

How to fix Volvo D12 engine problems – Image source:

Fuel Pump Malfunction

You will see that a malfunctioning fuel pump will cause the gauge to either not register any pressure or leak many times more quickly than a faulty regulator.

If you notice a drag when you are just beginning to speed up, this is another sign that your fuel pump is damaged. A peculiar sound might come from the pump.

One of the major culprits behind fuel pump failure is that the Volvo engine’s brushes are rusty and incapable of touching to transfer energy. 

In this case, the only solution is to replace the gasoline pump. You might do short-term solutions. But ultimately the problem will probably come back, and you’ll need to have a new pump soon. 

Fuel Injector Malfunction

If your engine continues to stall out despite having stable fuel pressure in the fuel pump and a functioning regulator, your injector is the cause.

The fuel injector plays a role in pumping fuel from the tank to the motor. No matter how high the fuel pump pressure is, the engine will not receive enough gasoline when the nozzles are blocked with dirt and oil.

The simplest solution is to clean the injector. However, if the problem is serious, you should buy a new injector. Before changing a new one, have a qualified technician inspect the complete fuel system to ensure that you will not throw out any component that is still functioning well in years to come.


What are the Volvo D12 engine problems? They are improperly running or stop working engines. The causes may come from the problem of idling, turbo, and coolant systems. Also, battery, alternator, wiring, and fuel system malfunction can lead to these engine problems.

You need to check your engine accessories and pay attention to their unusual signs to deal with them promptly. Visit an auto dealer or center to get full service.

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