Check engine light sensor

Throttle position sensor code. Check the wire is not damaged and the connected is secure. This is laced on the throttle body.
good luck

P2138 Throttle/Pedal Pos Sensor Voltage Correlation

Potential Causes of P2138 DTC It's been my experience that the wiring connector or "pig tail" on the throttle body gives problems in the form of a poor connection.The female terminals on the pigtail corrode or pull out of the connector. Possible bare wire on pigtail shorting to ground. The top cover on the throttle body distorted preventing the gears from turning properly. The electronic throttle body is faulty. The accelerator pedal sensor or its wiring failed. The engine management computer has failed. The TPS sensors were not correlating for a few seconds and the computer needs to be cycled through its relearn phase to restore active response to the throttle body, or the computer needs reprogramming at the dealer.

Generic OBD Error Code Details for P2183 Engine Coolant Temperature Sensor 2 Circuit Range/Performance
You could have a stuck open engine thermostat.

Here is the definition. You may need to have someone check the accelerator pedal position sensor and the circuit.

P2138 NISSAN Description The Accelerator Pedal Position (APP) sensor is installed on the upper end of the accelerator pedal assembly. The sensor detects the accelerator position and sends a signal to the Engine Control Module (ECM).
Accelerator pedal position sensor has two sensors. These sensors are a kind of potentiometers which transform the accelerator pedal position into output voltage, and emit the voltage signal to the ECM.
In addition, these sensors detect the opening and closing speed of the accelerator pedal and feed the voltage signals to the ECM. The ECM judges the current opening angle of the accelerator pedal from these signals and controls the throttle control motor based on these signals.
Idle position of the accelerator pedal is determined by the ECM receiving the signal from the accelerator pedal position sensor. The ECM uses this signal for the engine operation
such as fuel cut.
Read more: http://engine-codes.com/p2138_nissan.html#ixzz26J3D2x8s

DTC P2138 - TPS/Pedal Position Sensor/Switch D/E Voltage Correlation

Check wires and harnesses connections first, then its possible that the sensor go to bad.

Keep us updated.

P2138 is Throttle Pedal Position Sensor/ Switch D / E Voltage Correlation. Replace the Throttle Pedal Position Sensor/Switch.Remember to have the set code Cleared from the cars computer, this will turn off the check engine light and reset it. Good Luck and have a good XMASS.

There is a GM Technical Service Bulletin (TSB) on this issue, below is a summary;

#07-06-04-019A: Intermittent MIL/SES, DTC P2138 with Reduced Engine Power (Repair Instrument Panel (IP) to Body Harness Connector)

Models: 2005-2008 GM Passenger Cars and Light Duty Trucks (Including Saturn)
2005-2008 HUMMER H2
2006-2008 HUMMER H3
2005-2008 Saab 9-7X

Condition

Some customers may comment on an intermittent MIL/SES light Illuminated with a message center or an indicator that displays Reduced Engine Power. DTC P2138 - Accelerator Pedal Position (APP) Sensor 1-2 Correlation may be set. The voltage difference between APP sensor 1 and APP sensor 2 exceeds a predetermined value for more than a brief period. Refer to DTC P2138 in SI for further diagnostics.

Cause

On some vehicles, the IP to body harness connector, which carries the APP signal to the ECM/PCM, is located in the left hand kick panel area or inside the IP. Water intrusion into these areas could cause an electrical short in the APP circuits setting a P2138 code.

Correction

Note: Make sure that no add-on/aftermarket equipment is electrically connected to the APP signals or to the other ECM/PCM five volt reference or return lines. These can generate false P2138 and/or other ETC System DTCs. If there are other engine DTCs besides P2138, such as MAP sensor faults (i.e. P0107, P0108), resolve these first before attempting to diagnose P2138 DTCs.

Important: Refer to DTC P2138 in SI to confirm that the ETC pedal is operating correctly.

Locate the IP to body harness connector, which may be located in and around the left hand kick panel area or inside the IP. Check to see if there is a water leak into the area and repair as necessary. Use a water hose to determine the source of a water leak and effectiveness of repair. Some examples of potential water leaks are: A-pillar seals, sunroof drain lines (if so equipped) and windshield/cowl sealing. Finally, repair or replace the IP to body harness connector, making sure no corrosion or debris is left on or between the terminals.

Condition:
Some customers may comment on an intermittent MIL/SES light Illuminated with a message center or an indicator that displays Reduced Engine Power. DTC P2138 - Accelerator Pedal Position (APP) Sensor 1-2 Correlation may be set. The voltage difference between APP sensor 1 and APP sensor 2 exceeds a predetermined value for more than 2 seconds. Refer to DTC P2138 in SI for further diagnostics.

Cause:
On some vehicles, the IP to body harness connector, which carries the APP signal to the ECM/PCM, is located in the left hand kick panel area and if the kick panel is not sealed properly, water enters and causes a short in the APP circuits setting a P2138 code.

Correction:
Important: Do Not replace the accelerator pedal assembly.

Locate the IP to body harness connector, which may be located in and around the left hand kick panel area. Check to see if there is a water leak into the area and repair as necessary.

i have a 2004 acura tl an is giveing me code p2138

P2138 is the APP sensor (accelerater pedal postion). More than likely it is the sensor itself that is bad. Clear the code and see if the light comes back on, It may be an intermittent failure. The sensor is located under the hood by the right strut tower.