Code No. P2123: Accelerator Pedal Position Sensor (main) Circuit High Input

A power voltage of 5 V is applied to the accelerator pedal position sensor connector terminal from the engine-ECU connector terminal APS5.
The power voltage is earthed to the engine-ECU connector terminal APSE from the accelerator pedal position sensor connector terminal.
The sensor signal is inputted to the engine-ECU connector terminal APSM from the accelerator pedal position sensor output terminal.

The accelerator pedal position sensor converts the opening degree of the accelerator pedal into the voltage signal to input it to the engine ECU.
The engine ECU uses this signal to determine the amount of basic fuel injection.

Check Conditions

Ignition switch is in "ON" position
Accelerator pedal position sensor (sub) is normal
Accelerator pedal position sensor (sub) output voltage is 0.125 V or higher and 1.4 V or lower.
Diagnosis code No. P2124 is memorised.

Judgement Criterion

The amount of depression of the accelerator pedal is detected, using the accelerator pedal position sensor (sub) signal, which is calculated by taking half of the normal value.

Failed accelerator pedal position sensor
Open circuit or harness damage in accelerator pedal position sensor circuit or loose connector contact
Failed engine-ECU

DIAGNOSIS PROCEDURE

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions).

	Go to Step 2.

(1)Disconnect the connector, and measure at the wiring harness side.

(2)Measure the resistance between the accelerator pedal position sensor connector (APSE line) and body earth.
OK: Continuity (2 Ω or less)

	Go to Step 5.

	Go to Step 3.

	Go to Step 4.

	Repair the connector(s) or wiring harness.

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions).

	Replace the engine-ECU.

	The check is end.

	Replace the engine-ECU.