Service Information

Spark

DTC P0122, P0123, P0222, P0223, or P2135 - Without FX3

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0122: Throttle Position (TP) Sensor Circuit Low Voltage

DTC P0123: Throttle Position (TP) Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
5V Reference	P0122	P0122	P0123	-
Signal	P0122	P0122	P0123	-
Low Reference	-	P0123	-	-

The throttle body assembly contains a throttle position (TP) sensor. The TP sensor is mounted externally on the throttle body assembly. The TP sensor is a potentiometer which provides a signal voltage that changes relative to the throttle blade angle. The engine control module (ECM) supplies the TP sensor with a 5V reference circuit, a low reference circuit, and a signal circuit.

Conditions for Running the DTC

•	The ignition is ON.

•	The DTC runs continuously when the above conditions are met.

Conditions for Setting the DTC

P0122

The ECM detects that the measured throttle position sensor signal voltage is less than 0.3V.

P0123

The ECM detects that the measured throttle position sensor signal voltage is greater than 4.8V.

Schematic Reference

Engine Controls Schematics : Siemens ECM - LPG with LCP → Siemens ECM - Gas without FX3 or LCP → Delphi ECM - FX3

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, verify that the scan tool TP Sensor voltage parameter changes while slowly depressing the accelerator pedal from the rest position to wide open throttle.
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.

Circuit/System Testing

Ignition OFF, disconnect the harness connector at the B106 throttle position (TP) sensor.
Ignition OFF for 30 seconds, test for less than 5Ω between the low reference circuit terminal B and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.

Ignition ON, test for 4.8-5.2V between the 5V reference circuit terminal A and ground.

⇒	If less than the specified range, test the 5V reference circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K20 ECM.

⇒	If greater than the specified range, test the 5V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

Verify the scan tool TP Sensor voltage parameter is less than 0.3 volts.

⇒	If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

Install a 3A fused jumper wire between the signal circuit terminal C and the 5V reference circuit terminal A. Verify the scan tool TP sensor voltage parameter is greater than 4.8V.

⇒	If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.

If all circuits test normal, test or replace the B106 TP sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for engine control module replacement, setup, and programming