The throttle body assembly contains a throttle position sensor. The throttle position sensor is mounted to the throttle body assembly and are not serviceable. The throttle position sensor provide a signal voltage that changes relative to throttle blade angle. The engine control module (ECM) supplies the throttle position sensor with a common 5-volt reference circuit , a common low reference circuit, and a signal circuit. The throttle position sensor signal voltage decreases from greater than 4 V at idle to less than 1 V at wide open throttle.

P0122

The ECM detects the throttle position sensor signal voltage is less than 0.18 V for greater than 1 s or a cumulative of 10 s.

P0123

The ECM detects the throttle position sensor signal voltage is greater than 4.6 V for greater than 1 s or a cumulative of 10 s.

DTCs P0121 and P0123 are Type B DTCs.

DTCs P0121 and P0123 are Type B DTCs.

If there is a condition with the throttle body sensors the ECM defaults to reduced power mode for the entire ignition cycle, even if the condition is corrected.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the DTC information with a scan tool. DTC P0641 should not be set.

⇒	If a DTC is set, refer to Control Module References.

2. Clear the DTC information with a scan tool.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

1. Ignition OFF, disconnect the Q38 Throttle Body harness connector.

Note: The control module or the sensor may be damaged if the circuit is shorted to battery positive voltage.

2. Test for less than 5 Ω between the low reference circuit terminal 3 (X1) and ground.

⇒	If greater than the specified range, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

3. Ignition ON, test for 4.8-5.2 V between the 5-volt reference circuit terminal 1 (X1) and ground.

⇒	If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

⇒	If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

4. Ignition ON, verify that the scan tool Intake Air Flow Valve Position Sensor voltage parameter is less than 0.3 V.

⇒	If greater than the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

5. Connect a 3 A fused jumper wire between the 5-volt reference circuit terminal 1 (X1) and the signal circuit terminal 5 (X1). Verify the scan tool Intake Air Flow Valve Position Sensor parameter is greater than 4.89 V.

⇒	If less than the specified value, test the signal circuit for an open/high resistance or for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

6. If all circuits test normal, replace the Q38 Throttle Body.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.