P2138 Chevy Silverado (Meaning, Causes, and Fixes)

Most Chevy Silverado is equipped with several generic Onboard Diagnostic Trouble codes that notify about occasional internal electrical or mechanical failures, and one of the most common Diagnostic Trouble Codes that Chevy vehicle users often encounter is the P2138.

The P2138 OBD code notifies about Throttle body-related problems and especially pops up when the Engine Control Module detects a suspicious issue in the Acceleration Pedal Position Sensor.

In today’s article, I will explain everything you need to know about the P2138 trouble code, including its definition, causes, common symptoms, and how to diagnose and fix this error code with simple solutions.

What Does P2138 Code Mean On Chevy Silverado?

The P2138 code on Chevy Silverado means your vehicle’s Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected a problem with the Accelerator Pedal Position Sensors 1 & 2 correlation.

It means the signals PCM has received from these two Accelerator Pedal Position (APP) Sensors do not match each other.

But before explaining more details regarding this error code, let us check out the dissection of the P2138 code:

• p- Powertrain (System of components compelling the Chevy Silverado forward)
• 2-Generic malfunction code generated via ECM/PCM
• 1-Specific System related to the Throttle/Accelerator Pedal Position Performance
• 38-This specific information indicates that the electronic throttle body of the vehicle is not responding as expected to PCM input as directed via a signal generated from the Accelerator Pedal Position (APP) Sensor.

How Does the Accelerator Pedal Position (APP) Sensors Work on Chevy Silverado?

These APP Sensors deliver information to the Powertrain Control Module regarding driver throttle requests. The APP Sensor works like the brain of your vehicle.

In this process, the Throttle Body Position Sensor (TPS) & the Accelerator Pedal Position (APP) Sensor systems work combinedly to produce accurate reading information to direct the ECM.

After receiving that information from the APP sensors, PCM rapidly processes that information and moves the Throttle plate to mirror the pedal movement. There is an internal motor inside the throttle body assembly, which compels the throttle plate movement (opening and closing).

The Throttle Position Sensor or TPS sends appropriate feedback or signal to the ECM (PCM) so that ECM can always be informed about what is going on in the Throttle plate area.

The APP Sensor system is also commonly referred to as the drive-by-wire system. It delivers information about each (“D” & “E”) accelerator pedal position, the pressure/load capacity, and the speed on the gas pedal to the ECM.

Those two sensors have individual return wiring and different voltage range, but they must generate similar or close voltage results.

Thus, when the ECM/PCM detects different outputs from those Sensors, ECM assumes that there must be a foul play between these two Sensor’s signals.

When both sensors reading output does not correlate, PCM instantly sends a signal to trigger the P2138 error code to warn the user about the possible internal fault.

Is P2138 Code On Chevy Silverado A Serious Problem?

Unfortunately, the P2138 code on Chevy Silverado is serious because this error is related to the engine Throttle body’s workability for the smooth operation of the vehicle engine.

If there is an issue with the Throttle pedal and Throttle plate correlation, the Throttle body will no longer respond as it is supposed to and can even lead you to experience unpredictable incidents while driving your vehicle on the highways.

What Causes P2138 Code On Chevy Silverado?

Check out the potential causes behind the P2138 code on your vehicle:

• The P2138 error code might trigger due to a faulty or malfunctioning Throttle Position Sensor (TPS) or damaged electronic throttle body assembly.
• It can be the failing throttle Acceleration Pedal Position (APP) Sensor or damaged wiring/connector associated with these APP Sensors.
• This P2138 code might show up due to a malfunctioning or failed Throttle motor.
• Any Throttle Body Motor worn-out, broken, loose, corroded, or fouled connector/wiring can also trigger this code.
• Failed or bad Engine Control Module or Powertrain Control Module (due to outdated software) often sends false alarm signals, and users end up seeing these error codes come off.
• When the engine keeps stalling after stopping or the vehicle turns to the Limp Mode (reduced power mode), this error code will also show up.

Common Symptoms Of Getting P2138 Code On Chevy Silverado:

Let us learn the common symptoms that can give you initial warnings about the P2138 code & potential internal problems:

• Once you notice that the Check Engine Light (CEL) of your Chevy Silverado is staying on or keeps flashing, you should consider it as an early sign of such internal issues.
  Besides Throttle Accelerator Position Sensors failure, the CEL can also illuminate due to other problems. So, you can only confirm it after the OBD II scanner verification and proper diagnosis.
• You might also consider noticing a significant loss of engine power or seeing your vehicle turn to the reduced power mode automatically and will not speed up above a certain RPM level.
• Your vehicle will also show obvious signs of starting as well as acceleration difficulties and will continue to stall even after you turn it off.

How To Fix The P2138 Code On The Chevy Silverado?

Whenever you encounter or notice that the P2138 error code is popping on, either follow below explained effortless steps to get rid of that trouble code or take your Chevy Vehicle to the nearest professional workshop-

Video: How to Fix CHEVROLET P2138 Code With Easy DIY

1. Disconnecting the Old or Existing Accelerator Pedal

See, that is the Accelerator Pedal Position.

As you go down inside, where the Accelerator Pedal is assembled on your Chevy Silverado, you will find two Torx screws up in the top.

So, use a Torx screwdriver or wrench to take those two screws off.

Next, remove the lock tab and unplug the electrical connector to remove the pedal.

Here underneath, you see this little clip. What you must do is pop this clip out by pushing that little button in there.

Then the Accelerator Pedal will come off as a complete assembly, and after detaching the old one, the pedal will look like this.

2. Replace & Install the New one

After removing the pedal, bring a new Accelerator Pedal replacement part that matches your vehicle model.

Then, put the new one in the old pedal’s position and securely reattach those two screws.

Next, plug the connector and put the lock tab again just like it was before.

Once you have finished the installation task, do not forget to test drive your vehicle to ensure whether this replacement fixed the code, or your vehicle still has the P2138 code flashing.

How Much Does It Cost To Fix The P2138 Code on Chevy Silverado Vehicles?

Remember the final cost of fixing this code will highly vary depending on your vehicle’s model, damage severity, the current price of the replacement parts, and the labor rate of your area.

Mostly, the labor cost ranges between $75 and $150 per hour based on the local area rate.

Replacement Parts	Estimated Price
Throttle Body Actuator	$350 up to $700
Throttle Position Sensor	$185 up to $300
Accelerator Pedal Position Sensor	$130 up to $200
Wiring Repair/Replacement	$100 up to $1000

If you are taking your vehicle to the mechanic, they will spend at least one hour to diagnosis your vehicle thoroughly to determine actual error or fault and the diagnostic labor expense will be added with your main service bill.

Frequently Asked Questions (FAQs)

Final Thoughts

Seeing the P2138 code on Chevy Silverado vehicles is pretty common, but there’s no need to get panicked because it’s quite simple to fix this code.

From its definition to DIY techniques to fix it, I already explained everything regarding the P2138. Therefore, the next time it shows up on your vehicle Scanner, you know exactly what might be the reasons behind this error and what to do next.