VW Polo - noises from the engine compartment

In the above-mentioned vehicle type, it can happen that, while driving, unusual noises may be heard coming from the engine compartment. The noise occurs particularly in the speed range between approximately 1,800 rpm and 2,800 rpm under partial load. The noise is often described as a humming or booming sound. There is usually no error memory entry stored in the engine control unit.

The cause of this problem may be attributed to flow and resonance phenomena in the area of the tank ventilation system. Within the specified speed and load range, pressure oscillations may occur within the valve and hose system, which are then transmitted to adjacent components in the engine compartment.

If, during troubleshooting, no abnormalities are found in the peripherals – such as the engine mount, exhaust system, auxiliary units or adjacent add-on parts – the tank vent valve, including the associated hose routing, is to be checked. If no external damage or installation faults can be identified, replacing the tank vent valve, including the hose, in accordance with the manufacturer’s instructions may resolve the issue.

Checks should then be run to see that the hose guide has been put in place correctly and without any tension so as to prevent any further resonance or contact noises.

Once the cause of the fault has been eliminated, delete the error memory and then carry out a test drive.