P0123

DTC P0123 Throttle Position (TP) Sensor Circuit High Voltage




Circuit Description
The throttle position (TP) sensor circuit provides a voltage signal that changes relative to throttle blade angle. The signal voltage will vary from about 0.6 volts at closed throttle to about 4.5 volts at wide open throttle (WOT). The TP signal is one of the most important inputs used by the powertrain control module (PCM) for fuel control and many of the PCM-controlled outputs.

Conditions for Setting the DTC
- The ignition is ON.
TP sensor signal voltage is greater than 4.88 volts for a total of 0.78 second over a 1.5-second period.

Action Taken When the DTC Sets
- The PCM will illuminate the malfunction indicator tamp (MIL) the first time the fault is detected.
- The PCM will store conditions which were present when the DTC was set as Freeze Frame and in the Failure Records data.
- The PCM will use a default throttle position based on mass air flow and RPM.

Conditions for Clearing the MIL/DTC
- The PCM will turn the MIL OFF on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
- A history DTC P0123 will clear after 40 consecutive warm-up cycles have occurred without a fault.
- DTC P0123 can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.

Diagnostic Aids
Check for the following conditions:
- Poor connection at PCM - Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection.
- Damaged harness - Inspect the wiring harness for damage. If the harness appears to be OK, observe the TP sensor display on the scan tool while moving connectors and wiring harnesses related to the TP sensor. A change in the display will indicate the location of the fault.
- Faulty TP sensor - With the ignition key ON, engine OFF, observe the TP sensor display on the scan tool while slowly depressing the accelerator to wide open throttle. If a voltage over 4.88 volts is seen at any point in normal accelerator travel, replace the TP sensor.

If DTC P0123 cannot be duplicated, the information included in the Failure Records data can be useful in determining vehicle mileage since the DTC was last set. If it is determined that the DTC occurs intermittently, performing the DTC P1121 Diagnostic Chart may isolate the cause of the fault.

Steps 1 - 2:

Steps 3 - 7:

Steps 8 - 12:

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Chart.
7. Components that share the TP sensor 5 volt reference A circuit include the following device:
- EGR valve

Disconnect the component while observing the TP sensor display on the scan tool. If the reading changes drastically when this component is disconnected, replace the component that affected the reading.