Poor connection at the throttle body wiring connector (pigtail), with corroded or pushed-out terminals (OBD-Codes.com says this is the most common in its experience). Bare wire in the throttle body pigtail shorting to ground. Faulty electronic throttle body or throttle position sensor, including a distorted top cover that stops the gears turning properly. Failed accelerator pedal position sensor or its wiring. Failed engine computer (PCM), or one that needs a throttle relearn or reprogramming (per OBD-Codes.com).

Clean or repair the throttle body connector, or replace a damaged pigtail. Repair damaged or shorted wiring in the throttle or pedal sensor circuits. Replace the electronic throttle body. Replace the accelerator pedal position sensor (pedal assembly). Perform a throttle relearn, or have the PCM checked, reprogrammed or replaced.

P2138🔧 Electronic throttle control / throttle and accelerator pedal position sensorsStop and fix promptly

P2138: Throttle/Pedal Position Sensor D/E Voltage Correlation (Meaning, Causes, Fixes)

Q: What does P2138 mean?

P2138 means the engine computer has found that two position sensor signals in the electronic (drive-by-wire) throttle system don't agree with each other. Common causes are a poor or corroded connector at the throttle body, a faulty electronic throttle body, a failed accelerator pedal position sensor or its wiring, and less often a failed engine computer. Most modern cars use electronic throttle control: instead of a cable, a sensor on the accelerator pedal tells the PCM (engine computer) how far you're pressing it, and the PCM drives a small motor that opens the throttle plate. OBD-Codes.com explains that the throttle body has two built-in throttle position sensors, and the PCM constantly checks that their voltages agree; when they deviate for two seconds, P2138 sets. RepairPal describes the throttle position sensor on the throttle body and the pedal position sensor in the accelerator pedal assembly, and says the code sets when the PCM detects a problem with this sensor or its circuit. The letters D and E identify which two sensor signals disagree; which physical sensors they are depends on the vehicle, so check a service manual for yours. OBD-Codes.com notes some brands word it differently, such as 'Throttle position sensor circuit range/performance' on an Infiniti or 'Electronic throttle control system malfunction power management' on a Hyundai. It says P2135, P2136, P2137, P2139 and P2140 are diagnosed the same way.

Q: Can I keep driving with P2138?

Stop and fix promptly. Get this fixed right away. RepairPal rates P2138 'Urgent', meaning it can cause severe damage or harm the driver and passengers, and says the engine computer may limit the car to 20 mph or less (limp home mode). OBD-Codes.com warns that losing control over the throttle can be dangerous and lists stalling at stops, no acceleration, sudden loss of power at cruising speed or a throttle stuck at its current RPM. If the car loses power, won't accelerate or the throttle sticks, get safely off the road and don't keep driving it.

Reviewed 2026-10-23 · Based on 2 cited source(s)

What P2138 means

Most modern cars use electronic throttle control: instead of a cable, a sensor on the accelerator pedal tells the PCM (engine computer) how far you're pressing it, and the PCM drives a small motor that opens the throttle plate. OBD-Codes.com explains that the throttle body has two built-in throttle position sensors, and the PCM constantly checks that their voltages agree; when they deviate for two seconds, P2138 sets. RepairPal describes the throttle position sensor on the throttle body and the pedal position sensor in the accelerator pedal assembly, and says the code sets when the PCM detects a problem with this sensor or its circuit. The letters D and E identify which two sensor signals disagree; which physical sensors they are depends on the vehicle, so check a service manual for yours. OBD-Codes.com notes some brands word it differently, such as 'Throttle position sensor circuit range/performance' on an Infiniti or 'Electronic throttle control system malfunction power management' on a Hyundai. It says P2135, P2136, P2137, P2139 and P2140 are diagnosed the same way.

Severity: can I keep driving?

Stop and fix promptly

Get this fixed right away. RepairPal rates P2138 'Urgent', meaning it can cause severe damage or harm the driver and passengers, and says the engine computer may limit the car to 20 mph or less (limp home mode). OBD-Codes.com warns that losing control over the throttle can be dangerous and lists stalling at stops, no acceleration, sudden loss of power at cruising speed or a throttle stuck at its current RPM. If the car loses power, won't accelerate or the throttle sticks, get safely off the road and don't keep driving it.

Common symptoms

Check engine light on
Reduced engine power or limp home mode, with speed possibly limited to 20 mph or less (per RepairPal)
Stalling when coming to a stop (listed by OBD-Codes.com)
No acceleration or total lack of power (listed by OBD-Codes.com)
Sudden loss of power at cruising speed, or throttle stuck at its current RPM (listed by OBD-Codes.com)

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

Poor connection at the throttle body wiring connector (pigtail), with corroded or pushed-out terminals (OBD-Codes.com says this is the most common in its experience)
Bare wire in the throttle body pigtail shorting to ground
Faulty electronic throttle body or throttle position sensor, including a distorted top cover that stops the gears turning properly
Failed accelerator pedal position sensor or its wiring
Failed engine computer (PCM), or one that needs a throttle relearn or reprogramming (per OBD-Codes.com)

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

Read all stored codes. OBD-Codes.com says other codes often accompany P2138 and help pinpoint the problem.
Look up technical service bulletins (TSBs) for your vehicle and this code. OBD-Codes.com recommends this first.
Check a service manual for a throttle relearn procedure for your car. OBD-Codes.com says the computer sometimes needs to be cycled through its relearn after the sensors stop correlating briefly.
Unplug the throttle body connector and check for bent, missing or corroded terminals. Clean light corrosion, apply a small amount of dielectric grease and reconnect. A connector with damaged pins can be replaced with a new pigtail.
Inspect the plastic top cover on the throttle body for cracks or warping. OBD-Codes.com says a distorted cover usually means replacing the throttle body.
Handle the throttle body gently. OBD-Codes.com warns these parts are very sensitive and can be ruined by a single drop.

Typical fixes

Clean or repair the throttle body connector, or replace a damaged pigtail
Repair damaged or shorted wiring in the throttle or pedal sensor circuits
Replace the electronic throttle body
Replace the accelerator pedal position sensor (pedal assembly)
Perform a throttle relearn, or have the PCM checked, reprogrammed or replaced

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

The car goes into limp mode, loses power, stalls or the throttle sticks
The code comes back after cleaning the connector and doing any relearn
Testing needs a voltmeter and wiring diagrams. OBD-Codes.com says the pedal sensor should have a 5-volt reference and a signal that climbs smoothly from about 0.5 to 5.0 volts as the pedal is slowly pressed with the key on, and to replace it if the voltage spikes or there's no signal. It also says to check for power to the throttle motor at the throttle body while a helper presses the pedal: no power points to the computer, power present points to the throttle body.
RepairPal cautions that just replacing a sensor may not fix underlying issues, so diagnose before buying parts

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Can I drive with P2138?

It isn't a good idea. RepairPal rates it 'Urgent' and says the car may be limited to 20 mph or less, and OBD-Codes.com warns that losing throttle control can be dangerous, with possible stalling, no acceleration or a stuck throttle.

Is P2138 the throttle body or the gas pedal?

It can be either. OBD-Codes.com focuses on the throttle body and its connector and says the two throttle position sensors inside it disagree, but also lists the accelerator pedal sensor. RepairPal lists the pedal position assembly, the throttle position sensor, wiring and the PCM. Which sensors D and E are depends on the vehicle, so check the wiring and test before replacing parts.

Do I need a relearn after fixing P2138?

Sometimes. OBD-Codes.com says some vehicles need a throttle relearn procedure, or dealer reprogramming, to restore normal throttle response. The procedure varies by make, so check your service manual.

Why do the sources describe it differently?

OBD-Codes.com explains P2138 as the two throttle body sensors not correlating, while RepairPal describes a fault in the throttle or pedal position sensor or its circuit. Both name the throttle position sensor, the pedal sensor, wiring and the PCM as possible causes.

Sources

Last reviewed 2026-10-23. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.