Common Gripes and Quick Fixes with the Volvo V40 Throttle Position Sensor
The throttle position sensor is essential on just about any car. Even a classy family vehicle like the Volvo V40 requires this component to function properly. You see, it detects the position of the butterfly valve within your throttle in order to give the proper instructions to the mechanism that controls the valve. When you press down on the accelerator pedal, for example, the throttle position sensor first determines the state of the valve before it sends a signal that adjusts the valve accordingly. It even functions when the engine is idling-allowing for just enough of an opening on the valve to make sure the engine stays alive. There are a few things you can check to determine if you are having problems with your sensor.
"Check engine light" comes on
Granted, it's easy to confuse the check engine light warning with many different problems that can warrant the light coming on. The clue is actually something rather simple-and a bit funny: if the warning light comes on but your engine is still more or less fine, then there's a chance that your throttle position sensor is the one that's acting up. That means your engine is a-okay, and it's actually the sensor guiding it that is on the fritz.
Rough, near-stalling idling
Another symptom of trouble with your throttle position sensor is when you're on idle and the engine feels really rough-as though it wants to stall on you. The good news in this case is that the far more expensive engine isn't the one on the fritz-just the cheaper sensor. The reason that it causes all that roughing about is because the sensor-unable to tell what's what-keeps the butterfly valve in a position that isn't conducive to idling.
What to do?
The best thing you can do to deal with the problem temporarily is to easy up on the accelerator so you can make it to a mechanic. You could, hypothetically, do a repair on the module, but with sensitive calibrations involved, you're really better off replacing it.