P0122 on GMC
Throttle/Pedal Position Sensor/Switch 'A' Circuit Low Input
P0122 on GMC vehicles indicates throttle/pedal position sensor/switch 'a' circuit low input. Au7o has documented this code across 1 GMC model — most commonly on Terrain. This generic code means the PCM detected a lower-than-expected voltage from the throttle position sensor (or accelerator pedal position sensor) 'A' circuit. This sensor tells the computer how far the throttle/pedal is open so it can manage fuel, timing, and on drive-by-wire systems the throttle itself. A low or lost signal can cause hesitation, surging, poor acceleration, stalling, or limp-home mode, so it should be diagnosed promptly. Typical repair costs on GMC range from $250 to $650, depending on the specific model and root cause.
Common Causes of P0122
- •Faulty throttle position sensor
- •Short to ground or open in the TPS signal circuit
- •Damaged or corroded TPS connector
- •Loss of reference voltage or bad ground to the sensor
- •Worn throttle body / TPS contacts
- •Chafed or pinched wiring harness
- •Faulty PCM (rare)
P0122 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 P0122 across all makes →Frequently Asked Questions
What does P0122 mean on GMC?▼
P0122 stands for "Throttle/Pedal Position Sensor/Switch 'A' Circuit Low Input." This generic code means the PCM detected a lower-than-expected voltage from the throttle position sensor (or accelerator pedal position sensor) 'A' circuit. This sensor tells the computer how far the throttle/pedal is open so it can manage fuel, timing, and on drive-by-wire systems the throttle itself. A low or lost signal can cause hesitation, surging, poor acceleration, stalling, or limp-home mode, so it should be diagnosed promptly. On GMC specifically, this code is documented across 1 model.
What causes P0122 on GMC vehicles?▼
Common causes on GMC: Faulty throttle position sensor, Short to ground or open in the TPS signal circuit, Damaged or corroded TPS connector, Loss of reference voltage or bad ground to the sensor, Worn throttle body / TPS contacts. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0122 on a GMC?▼
Repair costs on GMC range from $250 to $650, depending on the specific model and root cause.
Which GMC models have P0122 documented?▼
Au7o has documented P0122 on 1 GMC model: Terrain.