P0120 Alert on Your 2024 Buick Enclave
The 2024 Enclave represents Buick's redesigned luxury crossover, and seeing "Reduced Engine Power" on its digital display is not the welcome you expected. P0120 indicates a throttle position sensor circuit malfunction in the drive-by-wire throttle system. The all-new 2024 Enclave features a 2.5L turbocharged four-cylinder engine, a departure from the previous 3.6L V6, but the electronic throttle system operates on the same GM TAC principles. The ECU has detected TPS signals outside the acceptable range and has responded by limiting engine power.
Symptoms to Watch For
- "Reduced Engine Power" warning message
- Check engine light on
- Dramatic loss of acceleration capability
- Throttle response delayed or erratic
- Idle speed fluctuating
- Vehicle may refuse to accelerate beyond 20-25 mph
Likely Causes
1. Throttle Body Defect
On a brand-new 2024 model, a manufacturing defect in the electronic throttle body is the primary suspect. The internal TPS potentiometer or drive motor may have left the factory with a defect that manifests after initial break-in miles.
2. Software Calibration Issue
The redesigned 2024 Enclave with its new 2.5T powertrain may need software updates that weren't available at build time. GM regularly releases calibration updates through dealer service bulletins.
3. Connector or Harness Assembly Error
A throttle body connector not fully seated during assembly, or a harness pinched during engine installation, can cause intermittent TPS circuit faults.
4. TAC System Communication Fault
The Throttle Actuator Control system links the pedal, ECU, and throttle body through a communication network. A CAN bus error or TAC module firmware issue can generate P0120.
5. Accelerator Pedal Sensor Defect
The pedal assembly's dual position sensors rarely fail on new vehicles, but a factory defect can produce conflicting signals that the ECU logs as a throttle circuit malfunction.
Diagnostic Approach
- Dealer scans with GDS2 for full diagnostic report and TSB search
- Check for pending software updates for the 2.5T powertrain
- Inspect throttle body connector for proper seating
- Monitor live TPS and APP sensor data for signal integrity
- Verify TAC module communication on the CAN bus
Repair Costs
- All repairs under warranty: $0
- Throttle body replacement (out of pocket): $300–$600
- Software update: $0 under warranty
- Connector/wiring repair: $0 under warranty
Can I Drive With P0120?
The Reduced Engine Power mode limits your Enclave to crawling speed. Do not attempt highway or highway-ramp driving. Use OnStar roadside assistance (included with your 2024 Enclave) to arrange a tow to the nearest Buick dealer. Throttle system faults are treated as priority repairs.
DIY vs Professional
Your 2024 Enclave is under GM's 3-year/36,000-mile bumper-to-bumper warranty plus the 5-year/60,000-mile powertrain warranty. Any throttle system repair will be covered at no cost. Do not attempt DIY repairs — take it to the dealer and let the warranty work for you.
Frequently Asked Questions
Is P0120 covered under Buick's warranty?
Yes. Your 2024 Enclave is fully covered under GM's bumper-to-bumper warranty (3yr/36k) and powertrain warranty (5yr/60k). Throttle system repairs are covered at no cost.
Why does my new Enclave say Reduced Engine Power?
The ECU has detected a fault in the electronic throttle system and limits power as a safety precaution. P0120 specifically means the throttle position sensor circuit is sending abnormal signals.
Will GM provide a rental car during the repair?
Buick dealers typically provide rental vehicles or courtesy transportation for warranty repairs that require the vehicle to stay overnight. Ask when scheduling your appointment.
Is the 2024 Enclave throttle body different from older models?
Yes. The 2024 Enclave uses a new 2.5L turbocharged four-cylinder engine with a different throttle body than the previous 3.6L V6. Parts are not interchangeable between generations.