P0121 on Pontiac
Throttle/Pedal Position Sensor Circuit Range/Performance
P0121 on Pontiac vehicles indicates throttle/pedal position sensor circuit range/performance. Au7o has documented this code across 1 Pontiac model — most commonly on G6. This code means the throttle position (or accelerator pedal position) sensor's signal does not match what the computer expects compared with other inputs like airflow, RPM, and the second throttle/pedal sensor. The sensor tells the computer how far the throttle or pedal is open; when its range or performance is off, the computer can't trust how much power you're requesting. You may notice hesitation, surging, poor acceleration, rough idle, or the vehicle dropping into a reduced-power 'limp' mode. It indicates an out-of-range or implausible signal rather than a complete loss of signal. Typical repair costs on Pontiac range from $250 to $500, depending on the specific model and root cause.
Common Causes of P0121
- •Worn or failing throttle position sensor
- •Dirty or carboned-up throttle body affecting plate position
- •Damaged, frayed, or shorted sensor wiring
- •Corroded or loose sensor connector
- •Poor sensor ground or reference voltage
- •Faulty throttle body / electronic throttle actuator
- •Mismatch between the two throttle or pedal sensor signals
P0121 on Pontiac by Model
Pontiac G6(1 issue)
- Reduced Engine Power / throttle limp mode (P2135, P0121, P2101)2006-2010
G6 owners frequently see a 'Reduced Engine Power' message with the car dropping into limp mode, triggered by throttle position sensor voltage-correlation faults. The throttle body's integrated TPS develops dirty or shorting solder points (sometimes attributed to 'tin whiskers') and corrosion at the connector, so the two throttle sensor signals disagree and the ECM cuts power for safety.
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View P0121 across all makes →Frequently Asked Questions
What does P0121 mean on Pontiac?▼
P0121 stands for "Throttle/Pedal Position Sensor Circuit Range/Performance." This code means the throttle position (or accelerator pedal position) sensor's signal does not match what the computer expects compared with other inputs like airflow, RPM, and the second throttle/pedal sensor. The sensor tells the computer how far the throttle or pedal is open; when its range or performance is off, the computer can't trust how much power you're requesting. You may notice hesitation, surging, poor acceleration, rough idle, or the vehicle dropping into a reduced-power 'limp' mode. It indicates an out-of-range or implausible signal rather than a complete loss of signal. On Pontiac specifically, this code is documented across 1 model.
What causes P0121 on Pontiac vehicles?▼
Common causes on Pontiac: Worn or failing throttle position sensor, Dirty or carboned-up throttle body affecting plate position, Damaged, frayed, or shorted sensor wiring, Corroded or loose sensor connector, 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 P0121 on a Pontiac?▼
Repair costs on Pontiac range from $250 to $500, depending on the specific model and root cause.
Which Pontiac models have P0121 documented?▼
Au7o has documented P0121 on 1 Pontiac model: G6.