Symptoms
Symptoms of a P2139 code can range from stalling when you stop, complete lack of power, no acceleration, sudden loss of power at cruising speeds, or a throttle stuck at the current RPM. Additionally, the check engine light will illuminate and the code will be set.
Potential Causes of P2139 DTC
Based on my experience, the wiring connector or “pigtail” on the throttle body causes issues in the form of a poor connection. The female terminals on the pigtail corrode or pull out from the connector.
- Possible bare wire on a pigtail shorting to ground.
- The upper cover of the throttle body is deformed, preventing the gears from turning properly.
- The electronic throttle body is faulty.
- The accelerator pedal sensor or its wiring has failed.
- The engine management computer has failed.
- The TPS sensors did not correlate for a few seconds and the computer needs to go through its relearn phase to restore active throttle body response, or the computer needs to be reprogrammed at the dealership.
Diagnostic Steps / Repair
A few points about the electronic throttle control. This system is incredibly sensitive and vulnerable to damage, more than any other system. Handle it and its components with extreme care. One drop or rough handling and it’s history.
Aside from the accelerator pedal sensor, the rest of the components are located in the throttle body. During inspection, you will notice a flat plastic cover on top of the throttle body. This houses the gears to operate the throttle plate. The motor has a small metal gear that protrudes through the housing under the cover. It drives a large “plastic” gear attached to the throttle plate.
The pin that centers and supports the gear fits into the throttle body housing and the upper pin fits into the “thin” plastic cover. If the cover is deformed in any way, the speed will be compromised requiring the complete replacement of the throttle body.
- The first thing to do is go online and get the TSBs (Technical Service Bulletins) for your vehicle regarding the code. These TSBs result from customer complaints or recognized issues 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, press and release the pedal 5 times. Wait 7 seconds, press and hold the pedal for 10 seconds. When the check engine light starts flashing, release the pedal. Wait 10 seconds and press the pedal again for 10 seconds and release. Turn off the ignition.
- Pull the electrical connector off the throttle body. Inspect it carefully 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 twisted or missing pins, you can buy a new “pigtail” at most auto parts stores or from the dealership.
- Inspect the upper cover on the throttle body for cracks or deformation. If there are any, call the dealer and ask if they sell just the upper cover. Otherwise, replace the throttle body.
- Using a voltmeter, probe the accelerator pedal sensor. It will have 5 volts for reference and next to it a variable signal. Turn the key and slowly press the pedal. The voltage should climb smoothly from 0.5 to 5.0. Replace it if the voltage jumps or if there is no voltage on the signal wire.
- Look online for the cable terminal identification on your vehicle’s throttle body. Probe the throttle body connector for power to the throttle motor. Have an assistant turn the key on and lightly press the pedal. If no power is present, the computer is faulty. If there is power, the throttle body is malfunctioning.