🚨 Diagnostic Profile
Vehicle Make: Buick
Code/System: Control Module Throttle Actuator Position Performance
Description: This diagnostic trouble code indicates that the Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected a performance irregularity in the Electronic Throttle Control (ETC) system. Specifically, the throttle actuator position sensor signals are not correlating as expected with commanded throttle inputs, meaning the module perceives a disagreement between where the throttle should be and where the sensors report it is positioned. This often stems from mechanical binding in the throttle body, carbon buildup, wiring harness faults, or internal actuator motor degradation.
🚨 Repair Difficulty Tier
Tier: Intermediate
This repair falls into the Intermediate category. While replacing a throttle body assembly is mechanically straightforward, accurate diagnosis requires a capable scan tool to view bi-directional live data (commanded vs. actual throttle plate angle) and perform a required Throttle Body Relearn/Reset Procedure after any repair. Failure to perform the reset procedure correctly can result in rough idle, stalling, or illumination of the Reduced Engine Power mode.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
Begin with a visual inspection of the throttle body assembly. Check for:
- Carbon or oil residue buildup on the throttle plate and bore, which can cause mechanical binding.
- Damaged, corroded, or loose electrical connector pins at the throttle body harness connector.
- Chafed or pinched wiring harness sections near the intake manifold or engine mounts.
- Any aftermarket intake modifications or vacuum leaks near the throttle body gasket.
Step 2: Diagnostic Verification
Using a capable scan tool (OEM GM MDI/Tech2 preferred, or a quality aftermarket scanner with bi-directional capability):
- Access live data streams for Throttle Position Sensor (TPS) 1 & 2 and compare them against Accelerator Pedal Position (APP) 1 & 2 signals.
- Command the throttle plate open/closed using bi-directional controls and observe if actual position matches commanded position within expected tolerance (~2-3%).
- Perform a resistance and voltage drop test across the throttle actuator motor circuit using a digital multimeter if live data appears erratic or unresponsive.
- Check for any stored freeze frame data indicating the conditions (RPM, load, temperature) present when the fault occurred.
Step 3: Resolution & Reset Process
If mechanical binding or sensor correlation failure is confirmed:
- Clean the throttle body bore and plate using approved throttle body cleaner only if no carbon buildup is severe; avoid cleaner contact with electronic sensor components.
- If cleaning does not resolve the correlation fault, replace the throttle body assembly as a unit (sensors are typically non-serviceable separately on most Buick platforms).
- After replacement or cleaning, perform the Throttle Body Relearn Procedure via the scan tool’s Service Programming System (SPS) or Special Functions menu — this recalibrates the idle airflow and minimum/maximum throttle position parameters.
- Clear all stored DTCs and conduct a test drive through varying load conditions to confirm the performance fault does not recur.
📦 Parts, Labor, and Budget Estimates
Required Components/Software:
- Electronic Throttle Body Assembly (OEM recommended)
- Throttle Body Gasket/O-ring Seal
- GM Tech2 or MDI with GDS2 software (for relearn procedure)
- Digital Multimeter (for circuit verification)
Average Component Price: $180 – $420 USD (OEM throttle body assembly, varies by model year and engine displacement)
Estimated Labor Hours: 1.0 – 1.5 standard shop hours (includes diagnostic scan time, component replacement, and relearn procedure)