P0122

DTC P0122

Circuit Description

The throttle position (TP) sensor is used by the PCM in order to determine the throttle plate angle for various engine management systems. The TP sensor is a potentiometer sensor with a 5-volt reference circuit, a low reference circuit, and a signal circuit. The PCM provides the TP sensor with a 5-volt reference circuit and a low reference circuit. Rotation of the TP sensor rotor from the closed throttle position to the wide open throttle (WOT) provides the PCM with a signal voltage less than 1 volt to more than 4 volts through the TP sensor signal circuit. If the PCM detects an excessively low voltage, this DTC will set.


DTC Descriptors

This diagnostic procedure supports the following DTC. DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage

Conditions for Running the DTC

The ignition is ON.


Conditions for Setting the DTC

The TP sensor signal voltage is less than 0.2 volts.


Action Taken When the DTC Sets

The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

- The control module turns OFF the malfunction indicator lamp (MIL L) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

- Clear the MIL and the DTC with a scan tool.


Diagnostic Aids

- The PCM 5-volt reference circuits are internally connected within the PCM. If all the TP sensor circuits are OK, inspect the MAP sensor, and inspect the exhaust gas recirculation (EGR) valve for malfunctions.

- If the DTC occurs intermittently, performing the DTC P1122 diagnostic test may isolate the cause of the fault. Refer to DTC P1122.P1122

- For an intermittent, refer to Intermittent Conditions.Symptom Related Diagnostic Procedures

Test Description

DTC P0122 Steps 1-9:

DTC P0122 Steps 10-15:

The number below refers to the step number on the diagnostic table.

8. Malfunctioning components that share the TP sensor 5-volt reference circuit could cause a low voltage condition on this circuit.