AutoCodes – Lexus – P0123 Lexus

P0123 Lexus Code - Throttle / Pedal Position Sensor / Switch 'A' Circuit High Input

Quick Answer

The throttle position sensor is mounted on the throttle with motor body assembly and detects the opening angle of the throttle valve. Common causes include Faulty Throttle Position Sensor (built into Throttle Body Assembly), Throttle Position Sensor circuit is open or shorted, Throttle Position Sensor poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0123 Lexus indicates Throttle / Pedal Position Sensor / Switch 'A' Circuit High Input.
Common causes: Common causes include Faulty Throttle Position Sensor (built into Throttle Body Assembly), Throttle Position Sensor circuit is open or shorted, Throttle Position Sensor poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 11,418

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 23, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P0123 Lexus Description

The throttle position sensor is mounted on the throttle with motor body assembly and detects the opening angle of the throttle valve. This sensor is a non-contact type sensor. It uses Hall-effect elements in order to yield accurate signals even in extreme driving conditions, such as at high speeds as well as very low speeds.
As the valve closes, the sensor output voltage decreases and as the valve opens, the sensor output voltage increases. The Engine Control Module (ECM) calculates the throttle valve opening angle according to these signals and controls the throttle actuator in response to driver inputs. These signals are also used in calculations such as air-fuel ratio correction, power increase correction, and fuel-cut control.
The ECM uses the throttle position sensor to monitor the throttle valve opening angle. There are several checks that the ECM performs to confirm the proper operation of the throttle position sensor.
This sensor transmits two signals, if the output voltage difference between the two signals deviates from the normal operating range, the ECM interprets this as a malfunction in the throttle position sensor. The ECM illuminates the MIL and stores the Diagnostic Trouble Code (DTC).

OBDII Code P0123 Lexus - Throttle / Pedal Position Sensor / Switch 'A' Circuit High Input - AutoCodes.com — P0123 Lexus Code - Throttle / Pedal Position Sensor / Switch 'A' Circuit High Input

What does this mean?

What are the Possible Causes of the DTC P0123 Lexus?

Faulty Throttle Position Sensor (built into Throttle Body Assembly)
Throttle Position Sensor circuit is open or shorted
Throttle Position Sensor poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P0123 Lexus?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0123 Lexus code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.