What causes the Audi to report an unreliable boost pressure signal?

[DeJaxson]

Audi reports an unreliable boost pressure signal because the Audi 1.8T engine is a turbocharged intercooled engine. The intake pressure sensor is located between the intercooler and the throttle body: After passing through the air filter, air enters the compressor side of the turbocharger. At this point, the intake pressure is not the pressure entering the engine; it still needs to pass through the intercooler. After the air exits the intercooler, it enters the combustion chamber. Therefore, the intake pressure sensor is positioned between the intercooler and the throttle body. Function of the intake pressure sensor: The intake pressure sensor detects the absolute pressure in the intake manifold behind the throttle valve. Based on the engine speed and load, it detects changes in the absolute pressure within the manifold and converts this into a signal voltage sent to the electronic control unit (ECU). The ECU uses the magnitude of this signal voltage to control the basic fuel injection quantity.

[ORiley]

I previously encountered an issue where my Audi displayed an 'unbelievable boost pressure signal' warning. The car noticeably lacked power during acceleration, and the engine warning light came on. At the repair shop, the mechanic read the fault codes with a diagnostic computer and inspected the vacuum lines connected to the sensor, discovering a small cracked pipe that was leaking air. He explained that this 'unbelievable signal' issue usually stems from a few common causes: either the pressure sensor itself is faulty, the connecting pipes are leaking or crushed, the turbocharger's solenoid valve is stuck, or the turbocharger itself is failing—possibly due to carbon buildup jamming the vanes or severe wear. Fortunately, in my case, just replacing the pipe fixed the problem. However, a friend's car had a solenoid valve failure, which was much more expensive to repair. I recommend getting it checked immediately when this warning appears, especially since the loss of power at highway speeds can be quite dangerous.

[Adriana]

Having repaired Audis for over a decade, the "boost pressure implausible signal" is a common fault. In most cases, it's caused by a faulty pressure sensor - that component operates in high-temperature conditions near the turbo and tends to lose accuracy over time. Aging rubber hoses connecting the sensor that develop air leaks are also frequent issues, especially in northern winters when the pipes become brittle. Another common culprit is a sticking turbocharger solenoid valve causing significant boost pressure fluctuations. The most troublesome scenario involves worn turbo blades or shafts, often accompanied by a hissing sound during acceleration. My standard procedure involves first checking the data stream to observe whether the actual boost values fluctuate abnormally. I strongly advise owners not to ignore this fault code - prolonged low-boost operation can significantly worsen engine carbon buildup.

[Imogen]

My old Audi had this issue before, and the most noticeable symptom was a delayed response when pressing the throttle to overtake. The mechanic explained that there was a problem with the turbocharger control system: it could be a faulty sensor monitoring the boost pressure, or a leak in the tubing connected to the sensor. If the control valve on the turbocharger gets stuck due to carbon buildup, it can also cause this issue. I replaced the sensor at that time, and everything went back to normal—it cost me around 800 yuan in total. I recommend addressing this problem as soon as possible; otherwise, you'll feel a significant lack of power when climbing hills on the highway, and it will also consume much more fuel.

[MacCaroline]

Last week, my Audi suddenly displayed this fault, which scared me into pulling over immediately. Upon inspection, it was found to be an abnormal signal from the turbo pressure sensor: it could be that the sensor itself was faulty; or the pipe connected to the sensor might have been cracked by high temperature, causing an air leak; if the turbocharger's control valve was stuck by sludge or had poor electrical contact, the boost pressure would also become unstable. The mechanic said that if the turbo's internal components were damaged, it would be more troublesome. On the same day, the diagnosis revealed that the sensor connector was corroded and had poor contact, and it was resolved after cleaning. It is recommended not to delay repairs, especially since suddenly losing power while driving on the highway is very frightening and can also affect the engine's lifespan.

[SanAnderson]

The Audi reporting 'boost pressure not credible signal' usually indicates abnormal operation of the turbocharging system. There are four common causes: First, faulty pressure sensors leading to incorrect data; Second, cracked or blocked vacuum lines connected to the sensors; Third, stuck turbo solenoid valves unable to regulate boost pressure; Fourth, damage to the turbocharger itself, such as deformed blades or worn bearings. When I encountered this issue before, I noticed the engine RPM increased but the speed didn't improve accordingly. It's recommended to first check wiring connections and vacuum lines, then test the sensors. Not repairing this fault promptly not only affects driving experience but can also lead to incomplete combustion and increased carbon deposits.