Circuit Description
The throttle position (TP) sensor is mounted on the throttle body assembly.
The sensor is comprised of two potentiometers with common supply and ground circuits,
and independent signal circuits. As the throttle opens, the signal wire on sensor 1
reads a higher voltage, and the voltage on signal wire for sensor 2 decreases.
The ECM sets this DTC when the signal being received conflicts with the MAF reading.
DTC Parameters
DTC P0121 will set when:
| • | Battery voltage greater than 7 volts |
| • | Throttle angle percentages reported to ECM by TP sensor 1 and TP
sensor 2 differ by more than 6.30% |
| • | TP1 reading conflicts with current MAF reading |
P0121 is a (type A) DTC.
Diagnostic Aids
DTC P0121 indicates the TP sensor 1 value deviates more than 6.3% from
TP sensor 2 value, and MAF readings indicate TP sensor 1 is not functioning
correctly.
Possible causes:
| • | Check for adequate terminal tension |
| • | Water intrusion into connectors |
| • | Shifted (skewed) sensor |
