Unraveling P0120 in Your 2022 Buick Encore GX
When your 2022 Encore GX flashes "Reduced Engine Power" and the check engine light comes on simultaneously, the investigation leads to P0120 — a throttle position sensor circuit malfunction. The Encore GX rides on GM's VSS-F platform with either a 1.2L or 1.3L turbocharged three-cylinder engine, both using GM's electronic throttle body with an integrated TPS. These compact turbo engines rely heavily on precise throttle control, and when the TPS circuit reports values outside the ECU's expected range, the system goes into protective mode.
Clues You'll Spot
- "Reduced Engine Power" warning on the display
- Check engine light on
- Severely limited acceleration
- Engine feels gutless or won't rev past low RPM
- Idle may be rough or hunting
- Possible stalling in traffic
Top Suspects
1. Throttle Body Failure
The electronic throttle body on the Encore GX's small-displacement turbo engine works harder than on larger engines due to the turbo system's reliance on precise airflow metering. Internal TPS sensor wear or motor failure is the leading cause of P0120 on this platform.
2. Carbon Buildup in Throttle Body
The 1.2T/1.3T direct-injection engines produce crankcase vapors that coat the throttle bore. On a 2022 model with 20,000-40,000 miles, carbon deposits can impede throttle plate movement and corrupt position readings.
3. Connector or Wiring Issue
The compact engine bay of the Encore GX packs components tightly. Heat from the turbocharger can damage nearby wiring insulation or degrade the throttle body connector over time.
4. TAC System Fault
GM's Throttle Actuator Control system coordinates pedal input, ECU commands, and throttle body response. A communication glitch in this system can trigger P0120 even when the throttle body hardware is fine.
5. Accelerator Pedal Assembly
The dual-sensor pedal assembly can develop resistance issues, especially if subjected to moisture from wet shoes or spilled drinks. Degraded pedal sensor signals may be interpreted as a TPS circuit fault.
Diagnostic Steps
- Scan for codes with a GM-compatible scanner — note any TAC-related companion codes
- Inspect throttle body for carbon deposits
- Check connector pins for corrosion or heat damage
- Monitor live TPS data — voltage should read ~0.5V closed, sweep smoothly to ~4.5V open
- Test APP sensor at pedal — verify both sensor tracks respond proportionally
Cost Estimates
- Throttle body replacement (ACDelco): $200–$450
- Throttle body cleaning: $120–$250
- Connector/wiring repair: $100–$300
- TAC reprogram: $100–$200
- Pedal assembly replacement: $150–$300
Can I Drive With P0120?
In Reduced Engine Power mode, the Encore GX limits you to barely moving speeds. This isn't drivable in traffic. Have it towed to a Buick dealer or GM-certified shop. A 2022 model may still be within GM's 3-year/36,000-mile bumper-to-bumper warranty — check your mileage and purchase date before paying out of pocket.
DIY vs Professional
If under warranty, take it to the dealer — no cost to you. Out of warranty, throttle body replacement on the Encore GX is moderately accessible, but the relearn procedure requires a scan tool with GM TAC relearn capability. Throttle body cleaning is a reasonable DIY task if you're comfortable removing the intake piping on the turbo engine.
Frequently Asked Questions
What causes P0120 on a Buick Encore GX?
P0120 is most commonly caused by a failing electronic throttle body, carbon buildup restricting the throttle plate, or corroded wiring connections in the TPS circuit.
Can I reset the Reduced Engine Power warning myself?
Clearing the code with a scanner may temporarily remove the warning, but it will return if the underlying cause isn't fixed. The ECU needs the TPS circuit to function correctly before it releases the power limitation.
Is the Encore GX throttle body expensive?
An ACDelco replacement throttle body for the Encore GX runs $120–$200 for the part. With professional installation and relearn procedure, expect $200–$450 total.
How does P0120 differ from P0121 or P0122?
P0120 is a general circuit malfunction (erratic or out-of-range signal). P0121 is range/performance (signal within range but not matching expected pattern). P0122 is circuit low (signal below minimum voltage). All point to the throttle system but help pinpoint different failure modes.