P1120 - FAULT CODE - OBD2

P1120 FORD, LINCOLN, MERCURY: THROTTLE POSITION SENSOR OUT OF RANGE

P1120 AUDI, VOLKSWAGEN: HO2S SENSOR BANK 2 SENSOR 1 OPEN CIRCUIT

P1120 BMW, MINI: PEDAL POSITION SENSOR CIRCUIT

P1120 BUICK, CADILLAC, CHEVROLET, GMC, HYUNDAI, PONTIAC, SATURN: THROTTLE POSITION SENSOR CIRCUIT 1

P1120 INFINITI, NISSAN: SECONDARY THROTTLE POSITION SENSOR

P1120 LEXUS, TOYOTA: MALFUNCTION OF THE ACCELERATOR PEDAL POSITION SENSOR CIRCUIT

P1120 MAZDA, SUBARU: THROTTLE POSITION SENSOR OUT OF RANGE

Engine efficiency depends largely on accurate throttle plate control. For this reason, manufacturers have implemented a sensor in the throttle bodies that has the exclusive function of monitoring the position of the throttle plate, from idle speed to Wide Open Throttle (WOT) conditions. For example, when the throttle is pushed to the bottom.

A basic description of the throttle body is that it is a simple potentiometer linked directly to the throttle plate motion control shaft. The throttle position sensor is connected at one end to a reference voltage provided by the PCM, and the slider part of the sensor is connected to the PCM via a dedicated signal circuit. When the throttle plate is closed, the slider part of the sensor is near the reference voltage point and enters the resistive strip. It causes a relatively high voltage to be passed to the PCM, which tells it that the throttle is in the closed position. But as the throttle opens, progressively less current is returned to the PCM, resulting in increased resistance as the sensor moves away from the reference voltage point.

The PCM understands the various voltage signals as changes to the effective throttle opening. It makes changes to the injector pulse width with that data and sets the ignition timing so that the engine operates efficiently. If the PCM detects that the real location of the throttle plate  the expected position, the diagnostic code P1120 OBDII will be set.

• The Check Engine light is illuminated.
• Remarkable degrees of engine power loss.
• Irregularities in the operation of the engine during idling.
• Gear changes are erratic.
• Fail-safe mode activated.

The reasons why the fault code P1120 OBD2 is stored are the following:

• Throttle Position Sensor wiring or connectors may have damage that causes a short or open circuit.
• The Throttle Position Sensor may be misaligned or defective.
• Possibly the throttle body or plate is defective.
• If the throttle body was replaced, the process of relearning the throttle position might not have been carried out.

The steps to follow to fix the DTC code P1120 OBDII are the following:

• Check the source of the vehicle information to access the TSB. These bulletins contain very useful information.
• Check the Throttle Position Sensor electrical circuit components for common damage such as wear, corrosion, or burns. Make the necessary repairs or changes.
• Check the throttle plate for high carbon residues that may prevent it from performing properly. If the plate has to be repaired or replaced, make sure that the position of the accelerator has been programmed into the sensor.
• Check the Throttle Position Sensor. Follow the steps indicated by the manufacturer regarding this diagnosis. Compare the readings with the specified ones. If you detect significant differences, make the appropriate improvements.