P0491 and P0492 concern insufficient secondary-air flow for banks one and two respectively. Ross-Tech’s VAG references include electrical supply, valves, hoses, sensing and obstructed air passages. Hearing the pump run is only one observation in that system.
Note whether one bank or both are affected
Keep both codes and their occurrence conditions in the report. A fault affecting shared equipment may produce different evidence from a restriction limited to one bank. The exact engine layout determines which components are shared.
Describe the cold-start behaviour and any pump noise, but do not infer measured airflow from noise alone. The garage should record the relevant command, supply and system response using the applicable test procedure.
Do not replace the ECU to solve a blocked passage
Electrical testing and physical airflow checks answer different questions. Ask which findings support the proposed repair. Model-specific software or cleaning guidance must match the engine and market before it is applied.
AXION can discuss supported control-circuit enquiries with the complete scan and test results. The bank-two reference complements the source below. Repair the functioning emissions system through the appropriate route; suppressing its codes does not establish that the original fault has been resolved.
Arrange an assessment
For ECU testing and repair, send the vehicle details and fault report to AXION. We support enquiries from drivers and garages. Workshop, postal and remote options depend on the job and are confirmed before booking.
Technical reference
Read the supporting technical documentation. The referenced design or vehicle application defines its scope; it is not a universal repair procedure.
Related reading
P052E crankcase ventilation faults with a whistle or engine warning. Browse the automotive electronics repair library for other systems and symptoms.