P2176: Throttle Actuator A Control System - Idle Position Not Learned

P2176 says the closed rest position of throttle A could not be learned. At key-on or after shutdown the controller drives the plate onto its lower stop and stores the sensor values; if they stay outside the window after the permitted attempts, the code is set. GM's 2023 table 23OBDG07 aborts the learn when the plate misses the closed target by over 1.5 % or sensor 1 lies outside 0.33-0.58 V (sensor 2: 4.42-4.67 V), within one trip; GM's hybrid tables rate it Type A. Honda bulletin 13-042 cures false P2176 on 2013 Accord, Civic and Crosstour with software, GM PIP4573B blames frozen crankcase ventilation below -23 °C, and PIP4578B carbon. A Delphi patent describes repeated learn attempts. P218A is the throttle B code.

Symptoms

• Check engine lamp right after start
• High, surging or unstable idle
• Reduced engine power after a cold start

Most likely causes

• Carbon on plate and bore preventing a clean closed position
• Ice from a frozen crankcase ventilation holding the plate open
• Engine software misjudging the sensor signals (update available)
• Idle learn not performed after cleaning or module replacement

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the pedal and throttle connectors
2. Use live data to confirm that both sensors rise smoothly and consistently
3. Clean the throttle if it has carbon buildup
4. Run the relearn procedure with the scanner if the manufacturer requires it
5. Replace the part identified by the diagnosis

Good to know

• Repair difficulty: easy
• It can trigger limp mode.
• It affects emissions.

What each character of P2176 means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 1: Air and fuel
• 76: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2176?

Be careful: the car may suddenly lose power. If it goes into limp mode, get off the highway and calmly make your way to a repair shop.

What causes code P2176?

The most common causes are: carbon on plate and bore preventing a clean closed position; ice from a frozen crankcase ventilation holding the plate open; engine software misjudging the sensor signals (update available).

Related codes

• P218AThrottle Actuator B Control System - Idle Position Not Learned
• P2109Throttle/Pedal Position Sensor A Minimum Stop Performance
• P2119Throttle Actuator A Control Throttle Body Range/Performance
• P0121Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance
• P0506Idle Control System RPM - Lower Than Expected

Sources

• gsi.ext.gm.com: 23OBDG07
• gsi.ext.gm.com: 11OBDG01 HYBRID Diagnostics
• static.nhtsa.gov: MC 10115198 9999
• static.nhtsa.gov: MC 10114468 9999

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.