P23AA: Turbocharger/Supercharger Bypass Valve A Stuck

P23AA concerns bypass valve A of a turbocharger or supercharger, which opens a path around the compressor to relieve boost when the throttle closes or at part load. The code means the valve no longer follows its command and sits fixed. GM applies P23AA to the electronically positioned supercharger bypass valve of the 2019 Corvette LT5: if the measured position deviates from the target by more than 25 % for at least 1 s while the valve is barely moving (under ±10 % per second), 10 failures in 14 samples at 6.25 ms set a Type A fault with the MIL in the first trip. The circuit codes P0033 to P0035 and the mechanical test P2261 cover other faults of the valve. Stuck open it costs boost and power; stuck closed it can cause compressor surge and noise on lift-off.

Symptoms

• Reduced boost and power
• Fluttering or surging noise when lifting off
• MIL on, possibly limited power mode

Most likely causes

• Valve or actuator mechanically seized (deposits, wear)
• Faulty electric actuator or position sensor of the valve
• Damaged linkage or valve plate
• High resistance in wiring or connector

What to check, in order

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

1. Check the hoses, clamps, and intercooler
2. Use the scanner to command the movement and compare the actual position with the requested one.
3. Compare commanded and actual pressure in live data
4. Check the actuator's movement
5. Check the vacuum hoses and the solenoid valve
6. Check the oil and the turbo shaft play before replacing it

Good to know

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

What each character of P23AA means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 3: Ignition and misfires
• AA: Specific fault in that system

Frequently asked questions

Can I keep driving with code P23AA?

Drive without demanding power and go to a repair shop soon. If you see a lot of blue smoke or hear a metallic noise, shut off the engine.

What causes code P23AA?

The most common causes are: valve or actuator mechanically seized (deposits, wear); faulty electric actuator or position sensor of the valve; damaged linkage or valve plate.

Related codes

• P0033Turbocharger/Supercharger Bypass Valve A Control Circuit
• P0034Turbocharger/Supercharger Bypass Valve A Control Circuit Low
• P0035Turbocharger/Supercharger Bypass Valve A Control Circuit High
• P2261Turbocharger/Supercharger Bypass Valve A - Mechanical
• P0299Turbocharger/Supercharger A Underboost Condition
• P0234Turbocharger/Supercharger A Overboost Condition

Sources

• law.cornell.edu: 13 CCR 1968.2
• gsi.ext.gm.com: 19OBDG03A Diagnostics

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.