Lower boost pressure with higher exhaust gas temperatures usually indicates what issue?

• A. Turbocharger failure or leakage
• B. Clean air filter blockage improves performance
• C. Overcooling the engine
• D. Exhaust leaks downstream of the turbo

Answer: (A)

Lower boost with higher exhaust gas temperatures points to the turbocharger itself not delivering reliably. When the turbo is healthy, exhaust energy turns the turbine to drive the compressor and raise intake pressure. If the turbo has a failure or leak—such as a damaged turbine, bad seals, or a compressor-side leak—the compressor can’t build boost, so boost falls. At the same time, exhaust energy isn’t being effectively used, so more heat stays in the exhaust, raising the exhaust gas temperature. This combination is a telltale sign of turbo trouble rather than a simple intake restriction or cooling issue. Other options don’t fit this pattern: a blocked air filter tends to degrade performance in other ways, overcooling reduces exhaust temperatures, and an exhaust leak downstream of the turbo doesn’t typically produce this same boost/EGT pattern.