P25B6: Turbocharger/Supercharger Wastegate B Stuck Closed

With P25B6 the second wastegate refuses to open when commanded, so turbo B cannot be regulated down and may push boost beyond the target; the module then usually caps torque. Ford detects it with the B-side position comparison (over 20 mm for 2.5 s, no P0247 or P2ABE present) and in 2024 files it as P0247 with type 73. A Ford case shows that loose hardware can trigger the closed-side codes too: TSB 24-2112 for the 2021–2023 Bronco with 2.7 L or 3.0 L engines lists P25B4, P25B6 and P0299 together and traces them to a loose nut on the turbo actuator arm, which leaves the valve out of its intended position and causes underboost. The same PCM update and later pinpoint advice as for P25B5 apply to 3.5 L EcoBoost trucks (TSB 23-2353, SSM 54083). Toyota lists P25B6-73 for the 2022 Tundra V35A.

Symptoms

• Power limited, sometimes after a short boost spike
• Check engine lamp on, possibly with P0299 or an overboost code

Most likely causes

• Loose nut on the turbo actuator arm (Ford Bronco TSB 24-2112)
• Wastegate B flap or spindle seized shut
• PCM software needing reprogramming (Ford TSB 23-2353)
• Actuator B unable to drive the valve open

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 P25B6 means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 5: Speed and idle
• B6: Specific fault in that system

Frequently asked questions

Can I keep driving with code P25B6?

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 P25B6?

The most common causes are: loose nut on the turbo actuator arm (Ford Bronco TSB 24-2112); wastegate B flap or spindle seized shut; pCM software needing reprogramming (Ford TSB 23-2353).

Related codes

• P25B5Turbocharger/Supercharger Wastegate B Stuck Open
• P25B4Turbocharger/Supercharger Wastegate A Stuck Closed
• P0247Turbocharger/Supercharger Wastegate Actuator B
• P0234Turbocharger/Supercharger A Overboost Condition
• P0299Turbocharger/Supercharger A Underboost Condition
• P2ABBWastegate Position Sensor B Circuit Low
• P2ABCWastegate Position Sensor B Circuit High

Sources

• fordservicecontent.com: OBDSM2400OUTPUT 16Jul2024 WSM final V2 MCS7001
• static.nhtsa.gov: MC 10254159 0001
• static.nhtsa.gov: MC 10246128 0001
• static.nhtsa.gov: MC 10209013 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.