SYMPTOMS OF A BAD THROTTLE POSITION SENSOR
PURPOSE
The purpose of the throttle position sensor is to measure the position of the throttle plate and send it to the Engine Control Module (ECM). After the Engine Control Module receives this information, it’s able to add or reduce fuel, control idle, and communicate to the automatic transmission to adjust shifting points
LOCATION
A throttle position sensor will typically be located on the throttle body (the red arrow indicates the location of the sensor in the picture).
symptoms
engine light
The first symptom of a bad throttle position sensor is having an engine light on. Common trouble codes that can show up that are related to a faulty throttle position sensor are:
P0120,
P0121
P0122
P0123
P0124
Ensure you can access your car's diagnostic codes by acquiring an OBD2 scanner here.
shifting problems
The second symptom of a malfunctioned throttle position sensor is shifting issues. If you’re trying to increase speed when driving down the road and notice a hard or delayed shift, it could be caused by a bad throttle position sensor. When the Transmission Control Module is unable to accurately receive information from the Engine Control Module about the position of the throttle plate, it won't be able to make the shift at the perfect moment.
poor acceleration
The third symptom of a bad throttle position sensor is poor acceleration. Poor acceleration in your vehicle can occur when the throttle position sensor is not communicating the exact position of the plate to the ECM. This will prevent it from making the correct fuel adjustments, resulting in your car having a poor acceleration.
limp mode
The fourth symptom of a faulty throttle position sensor is having your car go into limp mode. Limp mode is a safety feature that gets activated to protect you and your car. You'll feel your car a lot slower when driving. The RPMs and speed will be limited and your vehicle will usually be stuck in second or third gear. The throttle position sensor is responsible for communicating the throttle position to the ECM to make the correct fuel and shifting adjustments. If it fails, your safety will be at risk. That’s why your car goes into limp mode.
Before concluding that the throttle position sensor in your car is faulty, make sure to check the throttle body isn’t dirty. A dirty throttle plate can cause similar symptoms as discussed above. If you’ve concluded that it’s dirty, I would recommend cleaning it first before replacing the throttle position sensor. You can get a Throttle Body and Air-Intake Cleaner that I use here.
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