P2AB9: Wastegate Position Sensor A Circuit High

P2AB9 is logged when the wastegate A position signal climbs above its valid ceiling. Typical reasons are a signal wire shorted to the sensor supply or to battery voltage, an open ground return that lets the input float upward, or an internal sensor fault. GM's ECM checks the raw position as a share of the reference: above 95 % in the 2019 L3B tables and above 99 % in the 2025 tables, each with 10 failures in 12 samples and Type A, lamp in the first trip. Ford flags it above 4.50 V for 4 s and has reflashed 2021-22 F-150 2.7L trucks (TSB 22-2357) as well as 2020-23 Explorer, 2022-23 F-150 3.5L and Expedition/Navigator (TSB 23-2353) against false settings. With the flap position unknown, boost is held back. P2AB8 is the low side, P2ABC bank 2.

Symptoms

• Check engine light from the first trip
• Lower power under load, boost held back
• Powertrain fault (wrench) indicator on some Ford models

Most likely causes

• Signal wire shorted to the sensor supply or battery voltage
• Open sensor ground or corroded ground terminal
• PCM calibration that sets the code falsely (Ford reflash for listed models)
• Position sensor inside the electric actuator failed

What to check, in order

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

1. Check the hoses, clamps, and intercooler
2. Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
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: medium
• It can trigger limp mode.
• It affects emissions.

What each character of P2AB9 means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• A: Hybrid or air and fuel
• B9: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2AB9?

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 P2AB9?

The most common causes are: signal wire shorted to the sensor supply or battery voltage; open sensor ground or corroded ground terminal; pCM calibration that sets the code falsely (Ford reflash for listed models).

Related codes

• P2AB7Wastegate Position Sensor A Circuit
• P2AB8Wastegate Position Sensor A Circuit Low
• P2ABCWastegate Position Sensor B Circuit High
• P2B81Wastegate Position Sensor A Circuit Performance
• P2B93Wastegate Position Sensor A Exceeded Learning Limit
• P0299Turbocharger/Supercharger A Underboost Condition

Sources

• gsi.ext.gm.com: 19OBDG03D Diagnostics
• gsi.ext.gm.com: 25OBDG03B
• fordservicecontent.com: OBD Operations Summary Gasoline 2020 2023
• static.nhtsa.gov: MC 10222308 0001

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.