2021 Audi A4 allroad Fuel Tank Pressure Sensor Replacement Cost

The sensor constantly reads pressure in the fuel tank, and is essential in testing the evaporative emissions (EVAP) system for leaks. The vehicle's computer expects a certain range of pressure in the fuel tank at any given time. If the sensor reports pressures that are unexpected, the computer will turn on the check engine light.

The most common symptom for a defective fuel tank pressure sensor is an illuminated Check Engine Light triggered by one or more evaporative system fuel tank pressure sensor related codes. Usually, there are no noticeable engine performance symptoms associated with a defective fuel tank pressure sensor.

The check engine light will illuminate any time there is an EVAP problem. Also, in some models, there may be a popping sound accompanying the check engine light, as the leak detection pump continuously attempts to pressurize the fuel tank.

A vehicle with an EVAP system issue can be driven, but may get lower fuel mileage and run roughly. Also, a vehicle with an EVAP system issue won't pass standardized state or federal emission testing. 

EVAP system issues happen at some point to almost every vehicle. While the fuel tank pressure sensor doesn't commonly go bad, it will tell you when you have a problem with parts that fail more often, such as the gas cap. The gas cap is the number one reason EVAP failures are recorded. 

When the EVAP system is checked, the purge valve and vent valve must be closed, and the pressure is monitored by the fuel pressure sensor. If that pressure drops with both valves closed, that means there's a leak in the EVAP system. The sensor is also used in testing vent valve and purge valve operation. When the valves are open, the pressure sensor reads the fuel tank pressure and will note a drop in pressure. If it doesn't drop, the purge valve or vent valve may be faulty.

Evaporative system diagnosis can be difficult and trouble codes can be triggered by sensors and components other than the fuel tank pressure sensor.

If the sensor itself is faulty, the technician will remove all connectors, clean the surface around the faulty part, and install a new sensor. The EVAP system will then be allowed to run self-diagnostics to test the repair. If leaks are present or other components have failed, the test will fail.

We recommend using a factory fuel tank pressure sensor replacement part and checking for any applicable software updates for the power train control module (PCM).