Symptoms of P2138 OBD II Trouble Code
- 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.
Common Causes of P2138 OBD II Trouble Code
- The first thing to do is go online and get the TSBs (technical service bulletins) for you vehicle relating to the code. These TSBs result from customer complaints or recognized problems and the factory recommended repair procedure.
- Check online or in a service manual for a possible relearn procedure to reset the computer. For example, on a Nissan, turn the ignition on and wait 3 seconds. Within the next 5 seconds depress and release the pedal 5 times. Wait 7 seconds, press, and hold the pedal for 10 seconds. When the check engine light begins to blink, release the pedal. Wait 10 seconds and depress the pedal again for 10 seconds and release. Turn the ignition off.
- Pull the electrical connector out of the throttle body. Inspect it closely for missing or bent female terminals. Look for corrosion. Clean any corrosion using a small pocket screwdriver. Place a small amount of electrical grease on the terminals and reconnect it.
- If the terminal connector has bent or missing pins you can pick up a new "pigtail" at most auto parts stores or from the dealer.
- Inspect the top cover on the throttle body for cracks or warping. If any are present, call the dealer and ask if they sell just the top cover. If not, replace the throttle body.
- With a voltmeter, probe the accelerator pedal sensor. It will have 5 volts for reference and next to it a varying signal. Turn the key on and slowly depress the pedal. The voltage should climb from .5 to 5.0 smoothly. Replace it if the voltage spikes or it has no voltage at the signal wire.
- Look online for wire terminal identification on the throttle body of your vehicle. Probe the throttle body connector for power to the throttle motor. Have a helper turn the key on and slightly depress the pedal. If no power is present, the computer is at fault. If there is power the throttle body is malfunctioning.