P0120 on GMC
Throttle/Pedal Position Sensor Circuit Malfunction
P0120 on GMC vehicles indicates throttle/pedal position sensor circuit malfunction. Au7o has documented this code across 1 GMC model — most commonly on Terrain. This code indicates a malfunction in the throttle position or accelerator pedal position sensor circuit. These sensors tell the computer how far the throttle plate is open or how far you've pressed the pedal, which the computer uses to control engine power and, on drive-by-wire systems, the throttle itself. When the signal is out of range, erratic, or doesn't make sense relative to other inputs, P0120 sets. Symptoms can include hesitation, surging, stalling, or the vehicle entering a reduced-power 'limp' mode for safety. Typical repair costs on GMC range from $250 to $650, depending on the specific model and root cause.
Common Causes of P0120
- •Failed throttle position sensor
- •Corroded or loose TPS/pedal sensor connector
- •Damaged or shorted sensor wiring
- •Carbon buildup or a sticking throttle body
- •Worn throttle body or throttle plate
- •Poor sensor reference voltage or ground
- •Faulty accelerator pedal position sensor
- •Faulty PCM/ECM (rare)
P0120 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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View P0120 across all makes →Frequently Asked Questions
What does P0120 mean on GMC?▼
P0120 stands for "Throttle/Pedal Position Sensor Circuit Malfunction." This code indicates a malfunction in the throttle position or accelerator pedal position sensor circuit. These sensors tell the computer how far the throttle plate is open or how far you've pressed the pedal, which the computer uses to control engine power and, on drive-by-wire systems, the throttle itself. When the signal is out of range, erratic, or doesn't make sense relative to other inputs, P0120 sets. Symptoms can include hesitation, surging, stalling, or the vehicle entering a reduced-power 'limp' mode for safety. On GMC specifically, this code is documented across 1 model.
What causes P0120 on GMC vehicles?▼
Common causes on GMC: Failed throttle position sensor, Corroded or loose TPS/pedal sensor connector, Damaged or shorted sensor wiring, Carbon buildup or a sticking throttle body, Worn throttle body or throttle plate. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0120 on a GMC?▼
Repair costs on GMC range from $250 to $650, depending on the specific model and root cause.
Which GMC models have P0120 documented?▼
Au7o has documented P0120 on 1 GMC model: Terrain.