VW Polo - check engine warning lamp on

With the above vehicle type, the check engine warning lamp in the instrument cluster may light up. In conjunction with this, a fault relating to the flow rate in the tank ventilation system may be stored in the error memory of the engine electronics, i.e. without any further abnormalities becoming noticeable in the vehicle’s driving behaviour.

If it is a case of the above-mentioned fault, and if no definite faults have been detected in the area of the tank ventilation system during the carrying out of diagnostic work, then special attention should be paid to the tank vent valve. The valve controls the targeted recirculation of the fuel vapours stored in the activated carbon canister into the intake tract. If the valve malfunctions, the required flow rate can no longer be regulated correctly. Consequently, the system functions outside its specified operating parameters, which affects the fuel-air mixture and may cause the check engine warning lamp to come on.

The vehicle manufacturer has already recognised the issue. If no other fault is found in the tank ventilation system during further troubleshooting, replacing the tank vent valve and also the activated carbon canister may resolve the issue. In addition, the system’s lines must be inspected in accordance with the manufacturer’s instructions and cleaned if necessary.

In such a case, contact the vehicle manufacturer or a workshop authorised by said manufacturer.

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