P2128 - THROTTLE / PEDAL POSITION SENSOR / SWITCH "E" CIRCUIT HIGH

P2128 OBDII diagnostic code means that the PCM (Powertrain Control Module) has encountered a high voltage in either the TPS (Throttle Position Sensor) or PPS (Pedal Position Sensor) circuit. The “E” designation mentioned in this code refers to a particular circuit or area of the sensor. For this reason, you should consult a vehicle information source.

The PCM is responsible for controlling the Drive-By-Wire (DBW) system, by means of a throttle motor actuator and Throttle Position Sensors. These sensors receive 5 volts reference volts along with a ground signal.

• Check Engine light illuminated.
• The throttle locks up at different rpm.
• Acceleration is limited or impossible.
• When the engine is left idle, power is lost.
• Cruise control is not available.

The reasons for the P2128 OBD2 fault code being set are:

• The circuit between the TPS Sensor, PPS Sensor, and PCM may be open or shorted.
• The Pedal Position Sensor or Throttle Position Sensor may be faulty.
• Perhaps there are faulty electrical connectors or wires.
• Possibly the DBW system actuator motor is bad.
• Defective ECM.

To troubleshoot the DTC P2128 OBDII code you should do the following:

• Check if there is a Technical Service Bulletin (TSB) available for your vehicle model.
• Check the cables along with the connectors leading to the throttle system. Repair or replace any of these components that do not comply with the conditions for proper system performance.
• Check the throttle plate for excessive carbon buildup. Clean it if required.
• Use an automotive scanner to check for voltage spikes and inconsistencies between the TPS Sensor, PPS, and PCM. You can also use a DVOM to check the data seen from each of these sensors. The voltage varies between 0.5 and 4.5, with the throttle closed and open, respectively. If you find inconsistencies in these values for one of the sensors, you should replace it.