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

General Description


Accelerator pedal position (APP) sensor A and accelerator pedal position (APP) sensor B determine the position of the accelerator pedal. At the same mechanical position, the signal voltage of APP sensor B is always by factor 2 smaller than the voltage of APP sensor A. By different checks it is guaranteed that on account of a single fault, the pedal value cannot be higher than the corresponding mechanical position of the accelerator pedal. Circuit continuity check and synchronization check are done at the powertrain control module (PCM). For the synchronization check of the APP sensors, the variance of both APP sensor signals is compared with the synchronization tolerance. If the variance is a specified value, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Continuous
Sequence
None
Duration
0.24 second or more
DTC Type
One drive cycle, MIL on

Enable Conditions
Condition
Minimum
Maximum
APP sensor A output voltage [APP Sensor A]
-0.45 V
5.1 V
APP sensor B output voltage [APP Sensor B]
-0.05 V
2.6 V
[ ]: HDS Parameter

Malfunction Threshold
The variance of voltage between half of APP sensor A voltage and APP sensor B voltage is greater than 0.094 to 0.134 V for at least 0.24 second.

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 A failure
APP sensor B failure
PCM internal circuit failure

Confirmation Procedure
Operating Condition
Start the engine, and let it idle.

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.