The turbocharger (or turbo) is essentially an air pump that feeds more compressed air to a gasoline or diesel engine, hence the reason why turbo engines are often referred to as "forced-induction" motors. More air means the engine can ingest more fuel, and feeding an engine with a significant volume of compressed air enables it to pump out more power and torque. Moreover, turbocharging smaller engines has enabled carmakers to produce cars that deliver exhilarating thrust with good fuel economy, all while minimizing turbo lag.
Turbochargers are mostly composed of two main parts: the turbine and the compressor. The former has a turbine wheel that spins using the kinetic energy of the rushing exhaust gases. Meanwhile, the compressor attaches to the turbine wheel via a forged steel shaft. As the turbine wheel spins, it also turns the compressor, which sucks and compresses the air. In turn, the compressed air feeds into the intercooler (or charge air cooler) before entering the intake manifold, where the air-fuel mixture combusts to produce power.
It all sounds good, but the turbo is a serviceable part and requires periodic care, maintenance, and diagnosis to deliver reliable boost pressures. Turbochargers are fairly durable and can last up to 150,000 miles or more, but neglect and lack of timely servicing can shorten their lifespan. Most of the time, turbochargers won't die instantly or suddenly, and they will exhibit noticeable warning signs before giving up the ghost entirely.
The check engine light is like the harbinger of doom for most car enthusiasts, but you should look at it more as a warning sign than a reason to panic. It could illuminate for a bevy of reasons, but a failing turbocharger will most likely trigger the check engine light and the P0299 error code after a quick OBD2 scan, indicating a turbo underboost condition or inadequate boost.
In addition, a P0299 fault code may indicate problems with the exhaust gas recirculation (EGR) system, a bad MAP sensor, restrictions in the air intake system, or possible vacuum leaks. But in most cases, it's most likely related to the turbocharger (or supercharger) in forced-induction cars.
Other diagnostic trouble codes (DTC) that may appear alongside P0299 include P2262 (turbo problems, wastegate issues, boost sensor failure, etc.), P0243-P0250 (wastegate solenoid, underboost, overboost, etc.), and P0235-P0242 (turboboost sensor, faulty wiring, etc.).
Turbocharged engines rely on the turbocharger for maximum power output. But if you notice a severe lack of oomph or mediocre acceleration when gunning it, the turbocharger is most likely the culprit, most especially in aging gas cars or older diesel trucks. When accompanied by a check engine light and a P0229 (or related) error code, sluggish performance from your turbocharged car could mean the turbocharger or its related components are failing.
It's the same thing if you notice a marginally unresponsive throttle pedal, delayed throttle response, or the inability to reach higher speeds. A bad turbo will be unable to deliver the desired boost pressure, which affects the overall driving feel and performance. Of course, other problems may cause your car to feel like a wimp, such as congested air filters or a clogged catalytic converter. However, a turbocharged engine that refuses to perform may signify a failing turbocharger.
The turbocharger of your vehicle's engine can spin 80,000 to 150,000 rpm, while high-performance turbocharged sports cars or heavy-duty diesel trucks can have turbos that spin up to 250,000 rpm. All that spinning produces heat and friction, which is compounded by the heat from the exhaust gases that spin the turbine wheel. It's why turbochargers need constant lubrication while operating, and they get it from oil, water, coolant, or a combination of both, depending on the engine type.
Like the engine, oil can leak or seep out due to worn seals or gaskets, and it's a similar deal with the turbocharger. Oil helps cool down and lubricate the turbo bearing housing and the shaft, ensuring a smooth and reliable operation. But when the oil seals and bearings of a turbo wear down or develop cracks, oil can begin leaking into the exhaust system, causing more smoke to emanate from the exhaust pipe. A leaking turbo will also consume more oil, and you can confirm that by periodically checking the dipstick. Excessive oil consumption and too much smoke from the exhaust and the turbo itself are telltale signs of a failing turbocharger.
The induction note of a well-tuned turbocharged engine adds to the exhilarating driving feel of a forced-induction vehicle. However, a failing turbo will make annoying sounds like whistling, rattling, or hissing noises upon starting the engine. It may also produce noticeable whining noises as the turbo spools up, and those noises could be caused by a damaged compressor or turbine wheel, a stuck turbo wastegate, worn bearings, or possible boost leaks.
Moreover, those strange, unsettling turbo noises caused by worn bearings or a damaged turbine wheel are most likely due to insufficient lubrication or contaminated oil. It goes without saying that sufficient oil plays a significant role in prolonging the service life of your car's engine and turbocharger. It's why turbo motors require a different type of oil and more frequent oil changes than naturally-aspirated engines. When in doubt, consult the owner's manual to determine the oil change intervals and the recommended oil viscosity of your turbocharged car.
According to turbo expert Garrett, more than 90% of turbocharger failures are due to oil starvation or contaminated lubricants, while less than 1% is due to shoddy manufacturing. In other words, turbo longevity has more to do with proper maintenance, since dirty oil (or the lack of it) will most likely lead to turbocharger failure. Not changing the oil frequently on a turbo car will contaminate the bearings, turbo shaft, and oil feed holes with abrasive carbon deposits, leading to eventual malfunctions or damage to the turbocharger.
Besides, adhering to periodic oil changes, there are things you can do to preserve the integrity of your engine's turbocharger as the miles pile up. Avoid turning off a hot turbo engine to mitigate carbon buildup, allowing it to cool down sufficiently before shutting it down. Meanwhile, idling the engine extensively is unhealthy for both turbocharged and naturally aspirated motors, so you should avoid it if you can help it. Lastly, avoid hard accelerations when the engine is cold. Give it time to warm up before spooling the turbo to ensure the bearings and shafting are sufficiently lubricated.