What is the P0120 fault number? What is Throttle/Pedal Position (TPS Sensor “A”) Circuit Malfunction? How do I fix the P0120 fault code What are the causes and symptoms of the P0120 error code?
What is the P0120 Fault code? What does it all mean?
For engine operation, the throttle position sensor (TPS) and accelerator pedal location (APP) sensors are crucial. When the powertrain control module, PCM detects abnormal voltage readings from one of these sensors, a code P0120 will be triggered. To better understand the code, let’s briefly explain how APP and TPS sensors work.
Sensors for TPS (Throttle Position Signal)
TPS sensors measure the throttle opening. There may be a variation in the number of TPS sensor depending on your vehicle’s make and year. Older vehicles that have a mechanical throttle linkage only come with a TPS sensor. Two sensors are required for vehicles with electronic throttle control (ETC). These sensors are usually located inside the throttle body assembly.
The PCM uses data from the TPS sensors to adjust idle speed and fuel delivery. ETC vehicles have data that can be used for throttle motor control and accelerator pedal control.
ETC vehicles are especially vulnerable to sensor failures. A failure of the sensor could cause the vehicle’s to enter safe mode. To avoid damage to other components, this mod slows down the vehicle’s speed.
The PCM provides a 5 Volt reference voltage and, usually, a ground to a throttle position sensor. At idle, the voltage is 0.5 Volts and at full throttle it’s 4.5 Volts. If the PCM detects the throttle angle being higher (over 2.5V) or lower than the recommended value for a given RPM it assigns fault code P0120.
Sensors for Accelelerator Pedal Position (APP)
Some vehicles may display code P0120, which could indicate a problem with one of the vehicle’s APP sensor. ETC vehicles have APP sensors as the primary input for throttle motor control.
If the PCM detects any deviation in the voltage signals coming from the APP sensor/TPS sensor, it will trigger code.
What causes the P0120 Fault code?
It can be difficult to identify the root cause of the problem. Here are some possible causes for code P0120 to give you an idea.
- – Defective throttle positioning sensor
- – Defective accelerator pedal position sensor
- – Connectors and cables that are damaged or corroded
- – A dirty or defective throttle body
- – Software that requires updating?
What are the symptoms of the P0120 Fault code?
- – Illumination at the check engine lights
- Engine could go out of control
- – Rarely, hard work on the vehicle
- – PCM controls fuel injector timing and engine speed
- – The vehicle can easily be driven slowly and with a very limited throttle response
- You may notice a change in the vehicle’s idle speed and it may not accelerate as much.
Note: The exact symptoms you experience will depend on which make and model your vehicle is and what the PCM strategy employed by the manufacturer.
How do I fix the P0120 fault code?
- – Repair or replacement TPS connector
- – Replacing or repairing the APP connector
- – Repair of circuit damage and wiring problems for both sensors
- Comparison of data from TPS sensor A circuit and B circuits
- – Replacing your TPS sensor
- – Replacing APP sensor
- – Checking and cleaning the throttle body.
How serious is the P0120 Fault code?
A P0120 code will cause the engine to enter safety mode. This can cause a variety of driving problems, including erratic idle speed and misfire, as well as a lack of acceleration. It is a serious code that must be corrected.
