Code
P1525
BUICK
P — Powertrain
Throttle Body Service Required
AI status
Completed
Completed
100%
Causes
- Carbon or dirt buildup on throttle plate/shaft causing sticking or incorrect position
- Faulty throttle body assembly (actuator or position sensor)
- Faulty accelerator pedal position (APP) sensor or related sensors
- Wiring or connector corrosion, opens, shorts, or poor grounds in throttle/APP circuits
- Low battery voltage or charging system faults during relearn/adaptation
- Intake vacuum leaks or severe air leaks altering idle and throttle control
Symptoms
- Malfunction Indicator Lamp (MIL) / Check Engine Light on
- Reduced engine power / limp-home mode
- Poor or delayed throttle response and hesitation
- Erratic or high/low idle, stalling at idle
- Surging or inconsistent acceleration
- Possible stored or pending related throttle/APP codes
What to check
- Connect a capable scan tool and read all stored/pending DTCs and freeze frame data
- Check battery voltage and charging system; test while cranking/idle
- Compare live data: accelerator pedal position vs commanded throttle vs actual throttle position
- Check for related codes for APP, ETB actuator, or wiring faults
- Perform visual inspection of throttle body, connectors, and wiring for damage, corrosion or contamination
- Inspect intake tract for vacuum leaks or disconnected hoses
Signal parameters
- Accelerator pedal position (APP) 0–100%
- Throttle valve / plate position (reported) 0–100%
- Commanded throttle position (%)
- Throttle actuator current or duty (manufacturer-specific units)
- Battery voltage (V) — nominal ~12–14.5 V
- Engine RPM (rpm)
Diagnostic algorithm
- Retrieve freeze frame and live data with scan tool; note APP vs commanded vs actual throttle correlation. Check for other codes.
- Verify battery and charging system voltage; repair battery/charging issues prior to further testing.
- Visually inspect throttle body, connectors, and wiring harness; repair any damaged wires or corroded terminals.
- With key on engine off, observe throttle plate movement via scan tool commanded positions; verify smooth movement and correct feedback. If stuck, perform physical inspection.
- If throttle plate is dirty or binding, perform safe throttle body cleaning per manufacturer procedure and actuate throttle after cleaning to verify movement.
- If sensors or actuator provide inconsistent or no feedback, test APP and throttle position sensors with multimeter/oscilloscope per factory values; replace failed components.
- Check for and repair intake vacuum leaks and ensure PCV/air intake are intact.
- If all hardware tests good, perform throttle/ETB relearn/adaptation procedure with scan tool or follow factory relearn steps; clear codes and retest on road.
- If fault persists after cleaning, wiring repair, and relearn, replace throttle body assembly and verify updated ECM software/calibrations if required.
- After repairs, clear codes and perform verification drive to confirm code does not return.
Likely causes
- Dirty/thick carbon deposits on throttle plate restricting movement
- Throttle body position sensor failure or loss of accurate feedback
- Throttle actuator motor degraded or intermittent
- Corroded connector or broken wire in ETB harness
- Failed APP sensor causing disagreement with ETB feedback
Fault status
Status
Throttle Body Service Required — ETB/Throttle control system fault detected. Inspect/clean throttle body, check sensors and wiring, perform relearn or replace faulty components as required.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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