Code 21 - TPS Signal Volt Hi (A/F/J/N/P Body)

The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to throttle valve. Signal voltage will vary from less than 1.25 volts at idle to 4.5 volts at wide open throttle. Code 21 will set if: TPS voltage is greater than 2.5 volts for 2 seconds, engine speed is less than 1600 RPM or if MAP is less than 9 psi or equal to a no load condition.

1. This test confirms Code 21, and that fault is present.
2. This test simulates Code 22. If the ECM recognizes the low voltage signal and sets Code 22, the ECM and wiring are okay.

Fig 1: Code 21 Flow Chart: TPS Signal Voltage High

Fig 2: Code 21 Flow Chart: TPS Signal Voltage High

Fig 3: Code 21 Schematic: TPS Signal Voltage High