P2138: How to Diagnose & Fix — Throttle/Pedal Position Sensor D/E Voltage Correlation
7 vehicles · 4 makes · $100-$700 repair
How to diagnose and fix P2138: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Chevrolet Avalanche · 2007–2013
The 2007-2013 Avalanche frequently enters "Reduced Engine Power" mode, severely limiting acceleration. The most common causes are the electronic throttle body wearing out or the accelerator pedal position sensor (APP sensor) developing faults. The vehicle becomes barely drivable in this mode, struggling to accelerate to highway speeds. The issue can occur intermittently before becoming permanent.
Common Symptoms
- "Engine Power Reduced" or "Reduced Engine Power" message on dash
- Vehicle struggles to accelerate past 20-30 mph
- Check engine light with P2128 or P2138 codes
- Intermittent power loss that resolves after restart
- Rough or hesitant throttle response
How to Fix
Diagnose with a scan tool to determine if the throttle body or accelerator pedal position sensor is the cause. Throttle body replacement costs $200-$400 parts and labor. APP sensor replacement costs $100-$250. A remanufactured throttle body from a quality source works well. Clear codes after repair and road test to verify.
What you need to diagnose it
The repair instructions explicitly call for reading stored codes. Use a scanner that can read the named code families before choosing a repair.The recommended scanner supports these code families; confirm your exact year, model and module coverage before buying.
ANCEL AD310 Classic OBD-II Scanner
Read & clear engine (P) codes
$20–$40View
As an Amazon Associate, we earn from qualifying purchases. Prices are approximate and may vary.
Reading and clearing the code is DIY work. Module replacement or reprogramming is not — most modules are VIN-programmed, so a new one does nothing until a shop codes it to your car. Check for an open recall or service bulletin before buying anything.
Sources for this issue (1)
Chevrolet Silverado 1500 · 2014–2022
A widely reported Silverado 1500 complaint is a sudden cascade of dash messages — 'StabiliTrak disabled,' then 'Service StabiliTrak,' 'Service Traction Control,' and finally 'Engine Power Reduced' — sometimes with a stumble or stall and limited throttle response. The most common root causes are a faulty accelerator pedal position (APP) sensor or throttle body (electronic throttle), but it is also frequently traced to poor/corroded ground connections and chafed wiring under the driver's door sill or at the underseat/main harness connector. Because it can drop the truck into reduced-power limp mode at speed, owners treat it as urgent.
Common Symptoms
- 'Service StabiliTrak' and 'Service Traction Control' messages
- 'Engine Power Reduced' / limp mode
- Throttle becomes unresponsive or truck stalls
- Multiple ABS/traction/stability lights at once
- Symptoms come and go (intermittent)
How to Fix
Scan for stored codes (commonly P2138 and related APP/throttle codes) and read live throttle/pedal data. Start by inspecting and cleaning the body grounds under the driver's door and the main harness connector (a known fix), then test/replace the APP sensor or throttle body as indicated. Apply any GM throttle-body or PCM software updates. Confirm the actual failed component before replacing the throttle body, as wiring/ground faults mimic sensor failure.
What you need to diagnose it
The repair instructions explicitly call for reading stored codes. Use a scanner that can read the named code families before choosing a repair.This issue involves C codes, which a basic engine-code reader cannot see.The recommended scanner supports these code families; confirm your exact year, model and module coverage before buying.
Autel MaxiCOM MK808S Diagnostic Tool
All-system diagnostics (25+ modules)
$350–$450View
As an Amazon Associate, we earn from qualifying purchases. Prices are approximate and may vary.
Reading and clearing the code is DIY work. Module replacement or reprogramming is not — most modules are VIN-programmed, so a new one does nothing until a shop codes it to your car. Check for an open recall or service bulletin before buying anything.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Accelerator pedal assembly with position (APP) sensor — 2014-2018 (K2XX generation)OEM23362231Cross-refDorman 699-213, A-Premium APP pedal (Amazon B0CFXK98R8, lists 2014-2018 Silv, GM 20972082 (superseded by 23362231)$86–$162
Only replace after confirming P2138/P2122-type codes are not caused by the door-sill body grounds or the underseat harness connector — c
- Electronic throttle body with sensor — 4.3L V6 (LV3), 2014-2021OEM12676296Cross-refGM 12632171 / 12671014 / 12669536 / 12648414 (all superseded, Standard Motor Products / Dorman aftermarket units sold as 2$100–$295
4.3L-only throttle body; do not use the V8 part. 2022 Silverado 1500 with 4.3L is not shown on the GMPartsGiant fitment (listed 2014-2021) — a 2022 4.3L owner should confirm by VIN.
- Electronic throttle body with sensor — 5.3L V8 (L83 / L84), 2014-2022OEM12713775Cross-refGM 12740725 (current supersession of 12713775), GM 12617792 (earlier 5.3L number cross-referenced by afterma, A-Premium / ADIGARAUTO aftermarket units listing OE 12617792$200–$359
Confirm the failed component with live TPS/APP data first; grounds and chafed underseat harness wiring are
- Electronic throttle body (87mm) — 6.2L V8 (L86 / L87), 2014-2021OEM12740727Cross-refGM 12678223 / 12729495 / 12733469 / 12620263 / 12713774 (all, GM 12678312 (2019-2021 6.2L listing on GMPartsGiant, itself $80–$200
6.2L uses the 87mm LT-family throttle body shared with Corvette/Camaro LT1 — not interchangeable with the 5.3L unit.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (1)
Jeep Grand Cherokee · 2011–2022
The electronic-throttle-control warning lamp and reduced-power or limp mode are protective responses, not a diagnosis that the throttle body has failed. Depending on the stored DTC and application, the factory path may lead to a stuck or contaminated throttle plate, throttle motor or position-sensor response, accelerator-pedal sensors, a five-volt supply fault, damaged wiring or terminals, or a PCM issue. The old card's thermostat shopping claim is not part of the cited ETC diagnostic path, and a throttle body should not be ordered from the warning lamp alone.
Common Symptoms
- Electronic throttle control warning lamp
- Reduced engine output, limited RPM, or limp mode
- Poor or absent accelerator response
- One or more throttle, pedal, voltage-supply, or actuator DTCs
How to Fix
Before clearing anything, record every PCM DTC, pending code, freeze-frame value, battery voltage, temperature, and the exact conditions under which reduced power occurred. Diagnose prerequisite five-volt-supply, throttle-position, accelerator-pedal, or other active faults in the order specified by the current factory procedure for that VIN and engine. For a P2111-style fault, inspect the throttle plate for binding or foreign material and run the scan-tool throttle-follower test, then test the motor circuits, connector terminals, and wiring as directed. For a pedal-correlation code such as P2138, follow the accelerator-pedal sensor and circuit procedure instead. Replace and relearn a throttle body only when the applicable test condemns it; do not buy a thermostat as an ETC rule-out part.
Owner tips & cautions
- WarningAn ETC lamp does not prove the throttle body failed. Save the codes and freeze-frame data before clearing them or disconnecting the battery.
- TipAsk the shop to name the exact DTC and the failed factory test step before approving any throttle-body, pedal, wiring, or PCM part.
Sources for this issue (2)
GMC Terrain · 2010–2017
Ford Edge · 2007–2014
Find P2138 by make
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P2138 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P2138 mean?
P2138 stands for "Throttle/Pedal Position Sensor D/E Voltage Correlation." This code means the two (or three) signals from the accelerator pedal position / throttle position sensors disagree with each other — specifically sensors 'D' and 'E', which are typically the redundant signals built into the electronic accelerator pedal. Drive-by-wire systems use multiple sensors that should track together so the computer can trust the driver's input; when their voltages don't correlate, the computer can't be sure of the requested throttle and sets this code. As a safety response it usually puts the engine into a reduced-power 'limp' mode. It generally points to the pedal sensor assembly or its wiring.
What are the most common causes of P2138?
The most common causes of P2138 are: Faulty accelerator pedal position sensor assembly, Corroded or loose pedal sensor connector, Chafed, shorted, or open wiring between pedal and ECM, Shorted-together signal wires in the pedal harness, Poor sensor ground or reference voltage, Moisture or contamination in the pedal connector, Faulty ECM/PCM (less common). The specific cause varies by vehicle.
How much does it cost to fix P2138?
Repair costs for P2138 range from $100 to $700, depending on the vehicle and root cause.
Which vehicles are affected by P2138?
Au7o has documented P2138 across 7 vehicle models from 4 manufacturers: Chevrolet, Ford, GMC, Jeep.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.