Possible causes

– Faulty throttle position sensor
– Throttle position sensor harness is open or shorted
– Throttle position sensor circuit poor electrical connection
– Faulty Engine Control Module (ECM)

When is the code detected?

Malfunction is detected when an excessively low or high voltage from the sensor is sent to ECM.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P0121 Description

The throttle position sensor (TPS) responds to the accelerator pedal movement. This sensor is a kind of potentiometer which transforms the throttle position into output voltage, and emits the voltage signal to the Engine Control Module (ECM). In addition, the sensor detects the opening and closing speed of the throttle valve and feeds the voltage signal to the ECM.
Idle position of the throttle valve is determined by the ECM receiving the signal from the throttle position sensor. This sensor controls engine operation such as fuel cut. On the other hand, the Wide open and closed throttle position switch, which is built into the throttle position sensor unit, is not used for engine control.

P0121 Information for specific makes

P0121 GMC
P0121 CHRYSLER
P0121 SUBARU
P0121 DODGE
P0121 JEEP
P0121 FORD
P0121 HYUNDAI
P0121 ISUZU
P0121 KIA
P0121 LEXUS
P0121 TOYOTA
P0121 MAZDA
P0121 MITSUBISHI
P0121 VOLKSWAGEN
P0121 AUDI
P0121 JAGUAR
P0121 CADILLAC
P0121 CHEVROLET
P0121 BUICK
P0121 2003 JEEP LIBERTY
P0121 2002 JEEP LIBERTY
P0121 2004 JEEP LIBERTY
P0121 2005 JEEP LIBERTY
P0121 2006 JEEP LIBERTY