DTC P2138

DTC P2138:  Accelerator Pedal Position (APP) Sensor A/B (Throttle Position (TP) Sensor D/E) Incorrect Voltage Correlation

General Description 

Courtesy of HONDA, U.S.A., INC.

Courtesy of HONDA, U.S.A., INC.

Accelerator pedal position (APP) sensor A and accelerator pedal position (APP) sensor B are potentiometers. They are installed on the accelerator pedal. When the accelerator pedal is pressed, APP sensors A and B detect the accelerator pedal opening value. The accelerator pedal opening value is converted to a signal in APP sensors A and B and transmitted to the powertrain control module (PCM) to compute the target position. APP sensor A is the primary control, and APP sensor B is a back-up of APP sensor A in case it malfunctions. Both sensors compare their output voltage to each other for malfunction detection. When the voltage difference of APP sensor B is out of a fixed range for a set time, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type 

Execution	Continuous
Sequence	None
Duration	300 milliseconds or more
DTC Type	One drive cycle, MIL on

Enable Conditions 

Condition
Vehicle	ON mode

Malfunction Threshold 

The APP sensor B voltage [APP Sensor B Voltage] is in the malfunction area based on the APP sensor A voltage [APP Sensor A Voltage] as shown in the figure below for at least 300 milliseconds.

[ ]: HDS Parameter

Courtesy of HONDA, U.S.A., INC.

Possible Cause 

NOTE:  The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

• APP sensor failure
• APP sensor A APS1 line short to APP sensor B APS2 line
• PCM internal circuit failure

Diagnosis Details 

Conditions for setting the DTC 

When a malfunction is detected, the MIL comes on and a Pending DTC, a Confirmed DTC, and the freeze data are stored in the PCM memory.

Conditions for clearing the DTC 

The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.