What Does the Engine Code P2138 Mean?

If your car displays the engine code P2138, then something is probably wrong with your throttle position sensors.
Written by Georgina Grant
Reviewed by Melanie Reiff
If your car displays the engine code P2138, then your car’s computer is receiving conflicting information about the position of your accelerator pedal. This can lead to trouble driving and prompt your Check Engine Light to turn on as a warning. 
When your engine malfunctions, your car’s computer will display a diagnostic trouble code (DTC) to help you identify the issue. You (or your mechanic) can read the code using an OBD-II scanner that gets plugged into the car.
To better understand why your Check Engine Light is on,
, the
car insurance
comparison app, has compiled the following guide to the P2138 engine code.

What does the engine code P2138 mean?

The P2138 engine code means that your car’s engine control module (ECM) has identified an issue with throttle position sensor D or throttle position sensor E (or both).
The ECM reads signals from both
throttle position sensors
to determine the angle of your accelerator pedal and allow your car to speed up or slow down according to your wishes. When the two signals differ by a certain amount, the ECM will communicate that there is a malfunction.

How much will it cost to fix?

The total
car repair
costs will depend on which component of the throttle control system is causing the problem, but diagnosing the problem should take about one hour. This might cost from $70 to $150, depending on the auto shop.

What can cause the P2138 engine code?

The P2138 may be caused by a number of issues, including:
  • A malfunctioning throttle position sensor
  • A malfunctioning accelerator pedal position sensor
  • A malfunctioning throttle body motor
  • ECM software issues 
  • Broken, frayed, corroded, or otherwise damaged wires that prevent signal transmission
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Common symptoms of the P2138 engine code?

Besides an
illuminated check engine light
, you might be warned of this problem if:
  • Your car won’t start at all or won’t start normally
  • Your car isn’t accelerating normally

How serious is the P2138 engine code?

The P2138 engine code is fairly serious, and you should get it inspected as soon as possible. If you notice your car stalling or even accelerating irregularly, you could risk endangering yourself or others on the road. 

Can I fix the P2138 engine code myself?

While it is possible to fix engine code P2138 on your own, this isn’t recommended unless you have quite a bit of car maintenance experience and knowledge. The inspection and repairs can be tricky, and you don’t want to risk further damaging your car. 
It’s best to take your car to a qualified mechanic, who can inspect the wiring and connections for any signs of damage.
From there, the mechanic will inspect and possibly replace any of these components:
  • Throttle position sensor D
  • Throttle position sensor E
  • Throttle body motor
  • Engine control module

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