P0121

Schematic:

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
This DTC will set when:
^ Battery voltage greater than 7 volts
^ TP1 and TP2 differ by greater than 6.3 percent for longer than 180 milliseconds

and

^ TP1 reading conflicts with current MAF reading

DTC 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:
^ Poor connections
Check for adequate terminal tension
^ Corrosion
^ Water intrusion into connectors
^ Shifted (skewed) sensor