The Honda Pilot has been a popular midsize SUV since its debut in 2003. It is a versatile vehicle that can accommodate up to eight passengers and offers a spacious interior, good fuel efficiency, and a comfortable ride.
However, like all vehicles, the Honda Pilot is not immune to issues, and one of the most common problems that Honda Pilot owners encounter is related to the P2138 error code.
P2138 Honda Pilot Code: Accelerator Pedal Position Sensor A/B Incorrect Voltage Correlation
As the name implies, P2138 is for “Throttle/Pedal Position Sensor/Switch Voltage Correlation,” triggered when the vehicle’s Engine Control Module (ECM) detects the signals from the two throttle position sensors, or the two accelerator pedal position sensors do not correlate.
The ECM disables the throttle response whenever this occurs and displays an illuminated warning light. An electronic throttle control system in a modern vehicle consists of an accelerator pedal position sensor and an internal motor that is controlled by an electronically controlled throttle body.
Two embedded throttle position sensors further enhance this, and the ECM monitors the entire process. A sensor sends the ECM information regarding desired throttle opening in response to the accelerator pedal depressing.
A voltage reading from the computer is sent to the electric motor, which opens the throttle plate. A voltage signal is communicated to the computer through the two throttle position sensors embedded in the throttle body.
Lastly, the computer monitors the correlation between these two voltage readings. If the voltages agree, then everything is working as it should. A P2138 code is triggered when a deviation persists for two or more seconds, indicating an internal system malfunction.
What Does All This Mean?
Honda Pilots with an advanced drive-by-wire throttle system can suffer from P2138, a generic powertrain error code.
It means that the “D” and “E” throttle position sensors on your Pilot do not agree on how far the throttle has been opened. It should be possible for them to have similar output voltages. They do not work in this instance.
- Pressing the gas pedal starts the engine.
- The Pilot’s PCM is notified about the accelerator position by the position sensor.
- The throttle position sensors detect how far the throttle is opened. The PCM analyzes this feedback, and its throttle position is adjusted accordingly.
- A satisfactory TPS system requires that the “D” and “E” signals agree with each other and the accelerator position sensor.
- It is set to P2138 if they don’t agree.
- The PCM, which controls the throttle body, receives a signal from the accelerometer position sensor on the gas pedal. It transmits that to the drive-by-wire throttle system on your Pilot.
It is advantageous to operate the throttle in this way since with a traditional gas pedal (drive-by cable), most of the torque is at the beginning of the throttle.
While with drive-by-wire, 20% of the torque is given by the computer if you press down 20%. Doing this allows the torque to be applied more gradually when using a drive-by-wire.
It prevents wear and tear on the vehicle’s engine and extends its service life. Furthermore, drive-by-wire provides the following benefits:
- Rev Limiting
- Traction control response
- Cruise Control
- Fuel economy
What Are The Possible Causes Of The Code P2138 Honda Pilot?
ECM failures commonly cause P2138 codes. There can also be issues with circuitry due to spoiled, corroded, or faulty connections.
In many cases, the setting of the code is caused by a defective throttle position sensor. In addition to the ECM setting of the P2138 code, a damaged throttle body, wiring, or sensors of the accelerator pedal will also cause the P2138 code to be set in the ECM.
Because of these problems, the ECM cannot gather and correlate voltages to keep the vehicle running smoothly.
A software update may be necessary if the ECM isn’t functioning normally, and you may have to replace it altogether in rare cases.
What Are The Symptoms Of A P2138 Code?
You may notice a sudden loss of power at cruising speeds if the code P2138 occurs. It is also possible that your vehicle will experience problems with acceleration, loss of power, and unresponsiveness when the engine is operating.
If the error code is set to indicate there is an issue, the Check Engine Light will also illuminate. Last but not least, you may find the throttle stuck at any RPM.
How Difficult Is It to Inspect a P2138 Code?
Since P2138 repair involves multiple steps and complicated components like throttle body assemblies and throttle position sensors, the inspection process is complex.
In this case, it should be handled by a qualified technician with experience working on these issues. You don’t want to try to DIY this issue yourself, as you could cause further damage to your engine if you do.
As a result, if the throttle body motor or assembly is defective or damaged, a technician will replace it. In addition to the throttle body motor, the wiring may also be repaired or replaced.
Replace the throttle position sensor and connect the wiring to the throttle position sensor as part of this process. When the ECM is defective and no longer functions properly, a technician may need to replace it.
Diagnosing Honda Pilot P2138 Trouble Code
P2138 codes can occur for a variety of reasons. In order to diagnose the cause of this code, you would need to speak with a mechanic.
Use a Multimeter to Examine the Wiring
Test your Honda Pilot’s throttle and accelerator position sensor voltage using a multimeter. You’ll need to replace the sensor if they are out of range.
Examine the Wiring for Opens/Shorts
There is usually an open or short in the wiring when P2138 occurs. Take a look at the pigtails that connect to the throttle position sensor to ensure there is no damage.
Despite not being the best place to begin. It is possible to correct P2138 on some vehicles by reflashing the PCM. Find out if any technical service bulletins cover your Pilot’s model year and engine by visiting NHTSA.
Although, you are probably better off contacting your local Honda dealer and asking the service department.
Common Mistakes When Diagnosing The P2138 Code
Having the throttle position sensor replaced after diagnosing the P2138 error code can be a big mistake.
It is one of the most common causes of the P2138 trouble code, but it is not always the cause. Testing every aspect of the circuit is always important to diagnose an electrical problem accurately.
Never use a hand or any other tool to manually open the butterfly valve in an electronic throttle body.
As a result, the electronic throttle body motor may suffer severe damage, and the vehicle may not be able to function. If you are working with electrical equipment, be sure to do so safely and cautiously.
How Serious Is The P2138 Code?
The P2138 trouble code is one that I would consider to be very serious. When my car does not accelerate properly or stalls on the side of the road, I will be late for work. Therefore, anyone with a P2138 fault code should have it resolved immediately.
Can I Still Drive with a P2138 Code?
Having the P2138 code in your car can make it more difficult to maintain control of your car’s acceleration, which qualified technicians recommend against.
Using your cell phone on the road can be extremely dangerous and cause accidents and damage to your and others’ vehicles. When the P2138 code appears on your dashboard, it is time to take your car to a certified service station right away.
The P2138 code can be tricky to diagnose, and it’s critical to get it right. Driving around with a computer-controlled throttle that is unsure how much throttle it’s giving your vehicle is unsafe. Hopefully, you will be able to fix your Pilot soon!