Toyota Sienna engine stalls or loses power when heater or AC is turned on on Toyota Sienna

Some Toyota Sienna owners report experiencing engine stalling or loss of power when the heater or AC is activated, which may be linked to issues with the fuel system, air intake system, or ignition system. Erroneous signals from the Mass Air Flow (MAF) sensor can trigger the check engine light and generate diagnostic trouble codes. Additionally, engine sludge problems have been reported, leading to symptoms such as poor fuel economy, excess smoke, louder engine noise, and low oil pressure. Owners, particularly of models from 1997-2002 and 2004-2007, have noted that oil sludge buildup can significantly impair engine performance. Moreover, some drivers have experienced a loss of power when slowing down, resulting in delayed acceleration, which may indicate underlying engine issues. It is recommended that affected owners consult a qualified mechanic for a thorough inspection to diagnose and resolve these concerns.