P0120 on Your 2024 Cadillac XT5: What We Found
A "Reduced Engine Power" warning on your 2024 XT5 sends a clear signal — the ECU has detected a throttle position sensor circuit fault. The 2024 XT5 continues with the proven 3.6L V6 (LGX) on the C1XX platform, but P0120 on a vehicle this new typically stems from manufacturing or software issues rather than component wear. The electronic throttle body integrates the TPS, and the ECU responds to out-of-range signals by limiting engine output.
What You'll Notice
- "Reduced Engine Power" warning message
- Check engine light on
- Significant acceleration limitation
- Throttle may feel unresponsive
- Idle may fluctuate
Likely Causes
1. Throttle Body Factory Defect
An internal defect in the ACDelco electronic throttle body — bad potentiometer, contamination, or motor issue — is the primary suspect on a low-mileage 2024 model.
2. Software Calibration Update
GM may have released a PCM calibration update after your XT5 was built. A software flash at the dealer can recalibrate throttle body parameters.
3. Assembly Connector Issue
A throttle body connector not fully latched during factory assembly allows intermittent TPS signal dropouts.
4. TAC Module Firmware
The Throttle Actuator Control system firmware may need updating to resolve communication timing issues between the pedal, ECU, and throttle body.
5. Ground Circuit Problem
A poor engine ground connection can cause voltage fluctuations across multiple sensor circuits, including the TPS.
Diagnosis
- Dealer GDS2 scan for full diagnostic report
- TSB and recall search for 2024 XT5 throttle issues
- Verify connector seating and pin condition
- Check for pending software calibrations
- Inspect engine ground connections
Repair Costs
- All repairs under warranty: $0
- Throttle body replacement (out of pocket): $300–$650
- Software update: $0 under warranty
Can I Drive With P0120?
Only at crawling speed in Reduced Engine Power mode. Use Cadillac's complimentary roadside assistance to tow it to the dealer. Do not attempt highway driving.
DIY vs Professional
Dealer only. Your 2024 XT5 is fully covered under Cadillac's 4-year/50,000-mile bumper-to-bumper and 6-year/70,000-mile powertrain warranties. All repairs are at no cost to you.
Frequently Asked Questions
Is P0120 common on the 2024 XT5?
It's not widespread, but electronic throttle faults can occur on any new vehicle. The warranty covers these situations.
Will the repair take long?
Software updates are same-day. Hardware replacement is typically 1-2 days depending on parts availability at the dealer.
Can this happen again after repair?
If properly diagnosed and repaired, P0120 should not recur. If it does, escalate with the dealer — GM has customer satisfaction programs for recurring issues.
Does Cadillac provide a loaner for warranty work?
Most Cadillac dealers offer premium loaner vehicles for warranty repairs requiring the vehicle to stay overnight.