P2138 on GMC
Throttle/Pedal Position Sensor D/E Voltage Correlation
P2138 on GMC vehicles indicates throttle/pedal position sensor d/e voltage correlation. Au7o has documented this code across 1 GMC model — most commonly on Terrain. 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. Typical repair costs on GMC range from $250 to $650, depending on the specific model and root cause.
Common Causes of P2138
- •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)
P2138 on GMC by Model
GMC Terrain(1 issue)
- Throttle Body / Throttle Position Sensor Failure - 'Reduced Engine Power' Warning2010-2017
First-generation Terrains (2010-2017) are prone to a sudden 'Reduced Engine Power' warning caused by a failing electronic throttle body. Carbon and grime build up inside the bore and the internal throttle position sensor (TPS) fails or reads erratically, causing the ECM to enter a limp/reduced-power mode that limits the vehicle to very low speed. This is a widely reported failure on the naturally aspirated 2.4L four-cylinder and 3.6L V6 engines and frequently appears alongside a 'Service StabiliTrak' message. The most commonly cited trouble code is P2135 (throttle/pedal position sensor voltage correlation). No NHTSA recall covers the throttle body; it is addressed through non-recall repair.
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What does P2138 mean on GMC?▼
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. On GMC specifically, this code is documented across 1 model.
What causes P2138 on GMC vehicles?▼
Common causes on GMC: 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. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P2138 on a GMC?▼
Repair costs on GMC range from $250 to $650, depending on the specific model and root cause.
Which GMC models have P2138 documented?▼
Au7o has documented P2138 on 1 GMC model: Terrain.