Siena Defective Accelerator Pedal

Greetings! The symptoms you describe certainly point to a potential issue with the throttle valve or the accelerator pedal module. Higher fuel consumption and poor starting are common indicators. Have you tried checking for any obvious obstructions or dirt around the throttle valve itself? Sometimes a simple cleaning can resolve minor issues. However, given the age of the vehicle, a failing accelerator pedal module is a definite possibility. Are there any unusual readings from the sensor?

Thanks for the reply! I haven't checked for obstructions yet, but I will do that first thing tomorrow. Where exactly is the throttle valve located? I'm not super familiar with the engine layout. Also, how would I check for unusual readings from the sensor on the accelerator pedal module? I don't have any fancy diagnostic tools.

The throttle valve is generally located between the air filter box and the intake manifold. You should see a butterfly valve inside that opens and closes as you press the accelerator. As for sensor readings without diagnostic equipment, it's quite tricky. You could try visually inspecting the wiring harness connected to the accelerator pedal module for any damage, but beyond that, getting it checked at a workshop would be wise to avoid further damage. They can pinpoint the exact problem and prevent it from escalating.

Okay, thanks for all the information! I think I'll take your advice and bring it to a workshop. It sounds like it could be more complicated than I initially thought. It was a defective accelerator pedal module, and the repair cost was 205€. Thanks again for pointing me in the right direction!