The Volvo S90 with turbo engine is prone to problems with lubrication, hoses, sensors and the EGR system (exhaust gas recirculation system). Owners regularly report issues with excessive oil consumption, cracking turbo hoses and failing mass air flow sensors, especially when service intervals are stretched too far. In practice the diesel versions turn out to be more reliable, provided you shorten the oil change interval. Curious which problems occur exactly and how to recognise them?
What are the most common engine problems with the Volvo S90?
The Volvo S90 has built a reputation as a luxury saloon with good driving characteristics, but under the bonnet there are a number of recurring technical weaknesses. In particular, the petrol versions with turbo engines suffer from problems directly related to lubrication, boost pressure and sensor operation. Many of these issues develop gradually and are often only noticed at a late stage.
The Volvo S90 is especially susceptible to lubrication problems of the turbo shaft. As soon as the oil flow to the turbo is disrupted or no longer optimal, bearings and shafts wear more quickly. This can lead to loss of power, unusual noises and even blue smoke from the exhaust. In practice, these are recognisable complaints that owners report to specialist workshops.
In addition to turbo problems, cracked turbocharger pipes are also often mentioned. These hoses are under high pressure and can crack due to ageing, heat or mechanical stress. A cracked hose causes boost loss, which means the engine delivers less power and in some cases triggers a warning light. Such problems are mainly found on cars with higher mileage or on examples that have been heavily used.
‘ It is important to recognise these in time, because continuing to drive with a damaged turbo can lead to more serious engine damage and expensive repairs. ’
How do you recognise a turbo fault on the Volvo S90?
A faulty turbo often gives off clear signals. It is important to recognise these in time, because continuing to drive with a damaged turbo can lead to more serious engine damage and expensive repairs. Owners report a number of symptoms that directly point to turbo problems.
Loss of power while accelerating is a frequently reported sign. The engine feels sluggish and does not respond to the throttle as it normally would. This may indicate a problem with boost pressure or a leak in the intake system. In addition, owners sometimes hear a whistling or howling noise from the engine bay. This sound is caused by the turbo shaft no longer being properly lubricated or the bearings starting to wear.
Blue smoke from the exhaust is another classic symptom. This smoke occurs when engine oil enters the combustion chamber, for example due to a leaking turbo seal. Increasing oil consumption can also be linked to this. Some owners notice that the oil level drops more quickly than normal, especially after longer journeys or under heavy load. Combined with jerky running or irregular response, this often points to a combination of turbo and sensor problems.
What role do sensors play in engine problems?
The Volvo S90 is equipped with various sensors that control the engine management. If a sensor fails or sends incorrect values, this can disrupt the operation of the turbo and fuel injection. In practice, three sensors are often mentioned as root causes of problems.
The oxygen sensor measures the composition of the exhaust gases and ensures the correct air-fuel ratio. If the oxygen sensor is faulty, the engine can run too rich or too lean, leading to power loss and sometimes even soot deposits or vibrations. The mass air flow sensor, which measures the amount of air drawn in, is also sensitive to contamination and wear. A failing mass air flow sensor can cause uneven idling, hesitation when accelerating and fault codes in the engine management system.
The turbo boost pressure sensor is a third point of attention. This sensor monitors how much pressure the turbo is generating and controls the wastegate. When the sensor fails or sends incorrect values, the engine can switch to limp mode or lose power. In some cases, the engine temporarily loses power, after which everything seems normal again. These kinds of intermittent faults make diagnosis difficult, but a diagnostic tool can read fault codes that help point towards the cause.
How do you solve excessive oil consumption?
Excessive oil consumption is a complaint that regularly crops up among S90 owners with turbo engines. The problem can have several causes, but is often linked to the functioning of the turbo itself. When the turbo seal becomes worn, engine oil can enter the turbo and end up in the combustion chamber via the intake system. This leads to blue-grey smoke and a more rapid drop in the oil level.
Another possible cause is blocked oil lines to the turbo. When lubrication is not optimal, bearings and seals wear more quickly. This not only causes turbo damage, but also increased oil consumption. It is therefore important to change the engine oil in good time and preferably follow a shorter service interval than the factory recommendation. Many owners choose to change the oil every 10,000 to 15,000 kilometres instead of the official 20,000 kilometres.
In addition to preventive maintenance, it is wise to have a diagnosis carried out immediately in the event of unexpected oil consumption. A workshop can check the turbo, oil lines and pistons for leaks or wear. If you continue driving with an oil level that is too low, you significantly increase the risk of costly engine damage.
‘ A dirty EGR valve (exhaust gas recirculation valve) can lead to irregular engine behaviour, power issues and increased fuel consumption. ’
Why is EGR cleaning important?
The EGR system (exhaust gas recirculation system), which routes exhaust gases back to the engine to reduce emissions, is sensitive to contamination. This applies particularly to turbo engines that are regularly used for short journeys or mainly in city traffic. Soot and carbon deposits build up in the EGR valve and connected pipes, preventing the valve from opening and closing smoothly.
A dirty EGR valve (exhaust gas recirculation valve) can lead to irregular engine behaviour, power issues and increased fuel consumption. In more severe cases, the engine management system may log a fault code and put the car into limp mode. This is recognised by a warning light on the dashboard and a limited rev range. Cleaning the EGR valve is in many cases sufficient to remedy the issues, but in cases of severe contamination, replacement may be necessary.
How often EGR cleaning is required depends on driving style. Owners who often make short trips or drive frequently in city traffic are well advised to have the EGR valve cleaned preventively every 30,000 to 40,000 kilometres. Diesel owners need to be extra alert, as diesel engines produce more soot and therefore suffer from blockages more quickly.
Are diesel versions more reliable than petrol?
In practice, the diesel variants of the Volvo S90 are generally less prone to turbo problems than the petrol engines, provided that maintenance is properly kept up. Diesel engines run at lower revs and are loaded differently to petrol engines, which, in combination with a shorter service interval, results in more reliable operation.
However, diesel variants do require discipline in terms of maintenance and driving style. It is important to regularly get the diesel particulate filter properly hot by taking longer trips on motorways or country roads. If the car is mainly driven in the city, the filter can become blocked and problems with regeneration can occur. For diesels too, it is wise to change the oil more frequently than the factory interval states. Many garages recommend an interval of 10,000 to 12,000 kilometres for diesel versions that are used intensively.
Fuel quality also plays a role. Lower quality diesel can lead more quickly to blockages in filters and injectors. Filling up at reputable fuel stations and using additives can help to keep the fuel system clean. Diesel owners who take these points into account experience significantly fewer problems with the turbo, EGR and sensors.
What are useful tips when buying a used Volvo S90?
If you are buying a used Volvo S90 with a turbo engine, pay attention to the service history and the signals the car gives during a test drive. A car that has been serviced on time is considerably less risky than one with long intervals or unclear documentation. Ask specifically about oil change frequency, any sensor replacements and whether the turbo or EGR has ever been cleaned or replaced.
During the test drive it is wise to pay attention to the following points:
- Power delivery during acceleration: the engine should respond smoothly and directly without hesitation or juddering.
- Noises from the engine bay: whistling or howling sounds may indicate turbo problems.
- Smoke from the exhaust: blue or dark smoke is a warning sign.
- Warning lights on the dashboard: always have fault codes read before making a decision.
A cold and warm start also provide a lot of information. Start the engine from cold and pay attention to smoke and noises. Then drive at least 20 kilometres to bring the engine up to operating temperature and test the car under load. Intermittent complaints often only appear once the engine is warm and the turbo is being used actively.
‘ Prevention is the best strategy with the Volvo S90 with turbo engine. ’
What preventive measures can you take?
Prevention is the best strategy with the Volvo S90 with turbo engine. By applying a few simple measures, you can significantly reduce the risk of expensive repairs. A shorter oil change interval tops the list. Change the engine oil every 10,000 to 15,000 kilometres instead of the factory interval of 20,000 kilometres. This improves turbo lubrication and reduces wear on bearings and seals.
Allow the engine to warm up gently before using full throttle. A cold turbo that is immediately heavily loaded wears out more quickly. After a hard drive, it is sensible to let the engine idle for a short while before switching the car off. This gives the turbo time to cool down and prevents overheating of the bearings.
Regularly check the hoses and connections in the engine bay for small cracks, oil residue or loose clamps. Minor leaks can have major consequences for boost pressure and power. If in doubt, have the engine read out with a diagnostic tool. Fault codes relating to turbo boost, air mass or mixture control often quickly point towards the cause, even before there are visible symptoms.
On the Carnews website you will find much more information about engine problems, maintenance tips and buying advice for various Volvo models and other brands. Discover how to recognise technical issues, which measures you can take and what to look out for when buying a used car. Read on and expand your knowledge about everything to do with cars.
Frequently asked questions
On the Volvo S90 the most frequent turbo problems concern lubrication of the turbo shaft, with loss of power, whistling noises, increased oil consumption and smoke from the exhaust as typical symptoms. Cracked turbo hoses or pipes are also regularly reported, which lead to boost loss and fault codes. Faulty sensors such as the turbo boost pressure sensor, mass air flow sensor and lambda sensor likewise regularly cause irregular driving behaviour and warning messages. In practice, owners complain of juddering during acceleration, a hesitating engine and whistling or howling noises as common turbo-related issues.
A Volvo S90 owner can recognise early turbo deficiencies by gradual loss of power, especially during hard acceleration or overtaking. Other signals are a new, clearly audible whistling or howling sound from the engine bay and brief hesitation or juddering when accelerating. Increased oil consumption, oil deposits around turbo or intake hoses and blue or dark smoke from the exhaust under load also point to early turbo damage. If one or more of these symptoms occur, prompt diagnosis at a specialist workshop is recommended to prevent further damage.
The underlying causes of turbo wear or failures on a Volvo S90 are mainly poor or disrupted lubrication (due to blocked/ageing oil lines or excessively long oil change intervals), leaking or cracked boost hoses and malfunctioning sensors (such as the turbo boost pressure sensor, mass air flow sensor or lambda sensor) which cause the turbo to be controlled incorrectly. General neglected maintenance and unfavourable use (lots of short trips, heavily loading a cold engine) also accelerate wear. You can prevent this by using shorter oil change intervals than the factory specification, regularly checking/replacing oil lines and hoses and having the car read out immediately in the event of fault codes or loss of power. It also helps to warm the engine up gently, let the turbo spin down briefly after heavy use and regularly get the diesel versions properly up to temperature for a clean intake and exhaust system.
With a faulty turbo in a Volvo S90 there are roughly three options: repair/overhaul of the existing turbo, replacement with a refurbished exchange turbo or fitting a completely new original turbo. An overhaul or exchange turbo generally costs around €700–€1,500 including labour, depending on the damage and engine type. A new original turbo at the dealer usually runs to around €1,500–€2,500 or more including fitting. Additional costs can arise if oil lines, hoses or sensors around the turbo also need to be replaced.
Shorten the oil change interval (for example to 10,000–15,000 km) and always use high-quality oil and filters to keep turbo lubrication optimal. Regularly check turbo and intake hoses for small cracks, oil traces and loose clamps and, if in doubt, have the engine read out for turbo boost and air mass sensors. After a cold start, allow the engine to warm up gently and avoid high revs and full throttle until operating temperature is reached. After longer motorway journeys or heavy use, do not switch the engine off immediately, but drive the last part calmly or let the engine idle briefly so that the turbo can cool down.