P2578 Turbo and boost pressure: circuit fault

By: Diagno editorial team · Updated: 2026-10-15

P2578 means: Turbo and boost pressure: circuit fault. The turbo pushes extra air into the engine. Drive gently and have the car checked soon. The repair usually costs about €60–300 in Estonia. The most common cause: connector loose, damp or corroded. Other possible causes: wire broken or chafed, faulty sensor or actuator.

What it means

The turbo pushes extra air into the engine. The computer found the boost pressure wrong or the turbo control not working. The car often goes into limp mode. The computer found a fault in the electrical circuit: the part, a wire, a connector or a fuse.

What you may notice

• Much less power (limp mode)
• Turbo whistling or hissing
• Black smoke
• Engine light on

What could be wrong

1. 1Connector loose, damp or corroded
2. 2Wire broken or chafed
3. 3Faulty sensor or actuator
4. 4Engine computer fault (rare)

Repair difficulty: Hard

What you can check yourself

First look at the connector and wiring: anything loose, melted or green with corrosion? Check the boost hoses, especially the joints and around the intercooler. An oily hose points to a leak. Best left to a workshop. It needs a diagnostic tool and experience.

How we fix it

1. We read the fault data on the diagnostic tool and check whether the fault is constant
2. We measure the circuit's supply, ground and signal
3. We repair the wire or replace the connector
4. If the wiring is fine, we replace the sensor or actuator

Standard SAE description: Turbocharger Speed Sensor Circuit