Why does my F-150 PowerBoost lose power when I hit the gas?

Short answer: Owners trace this to two main things: a weak auxiliary 12V battery under the rear seat, which dealers often skip, and a transmission behavior at low speed in 2nd gear that some only fixed with a new transmission. If you also get 'Stop Safely Now' with code P0AA6, the hybrid system shut down because it detected a high-voltage leak to the body. That needs a dealer diagnosis.

Symptom: Sometimes when you accelerate out of a turn or merge, nothing happens until you floor it, then the truck lurches. Some owners also get 'Stop Safely Now' and have to pull over or tow the truck.

What to check first

1. Have both 12V batteries tested, including the one under the rear seat.
2. Write down when it happens: speed, gear, rolling stop or turn.
3. Ask the dealer to read stored codes, including P0AA6.
4. Ask about known transmission concerns on your build date.
5. Run your VIN at nhtsa.gov/recalls and finish any open recalls.
6. Keep records of every visit in case lemon law or buyback becomes an option.

Likely causes

1. Weak auxiliary 12V battery under the rear seat. PowerBoost trucks have a second 12V battery under the rear passenger seat. One owner's dead pedal stopped after replacing it, and said dealers often don't check it. The 12V battery is the small battery that powers the computers, locks and screens. Hybrids still need it to wake up, even when the big hybrid battery is full.
2. Transmission behavior at low speed in 2nd gear. One owner could reproduce it rolling a stop at about 8 mph in 2nd gear and said the only fixes in a long f150gen14 forum thread were new transmissions.
3. Hybrid high-voltage isolation fault (code P0AA6). P0AA6 means the hybrid system found electricity leaking from the high-voltage system to the body, so it shuts down for safety. One owner's Stop Safely Now events left this code.
4. Starter/generator or wiring. Another owner replaced both 12V batteries and still got Stop Safely Now, and someone suggested the starter.

What it usually costs

Owners didn't post prices for batteries or transmission work. Hybrid parts and transmissions on these trucks are often still under warranty.

Is it safe to keep driving?

No pedal response while merging is dangerous. Until it's fixed, leave extra room and avoid tight merges. If 'Stop Safely Now' appears, pull over as soon as it's safe.

DIY or shop?

Testing and replacing the 12V batteries is DIY if you're comfortable. Transmission and high-voltage work is for a hybrid-certified Ford tech.

Recalls, bulletins and complaints in plain words

• Recalls: NHTSA's recall lookup lists many 2021-2024 F-150 recalls, including 22V188000 (2021 F-150: a false low transmission fluid pressure code may shift the transmission into neutral) and 23V896000 (2021-2023 F-150 with the heavy-duty axle: rear axle hub bolts may break). None we found are specifically about PowerBoost dead pedal. Check your VIN at nhtsa.gov/recalls. If your car is part of a recall, the dealer fixes it for free.
• Plain words: NHTSA's F-150 complaint lookup returned errors for every model year on 2026-11-03, so the complaint count below is zero only because no data came back. It does not mean there are no complaints.
• NHTSA complaints: 0 keyword-matched complaints for Ford F-150 (all, including PowerBoost) 2021–2025 (of 0 unique complaints queried, NHTSA complaints API by model year, queried 2026-11-03; keywords: powerboost, hybrid, loss of power, lost power, stall, dead pedal, no power) (NHTSA returned no data for 5 model-year queries). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In 2023 PowerBoost — intermittent dead pedal coming out of corners, dealer can't reproduce it on Reddit r/f150, a 2023 PowerBoost Lariat at about 53,000 km sometimes gets no response at all when accelerating out of a corner or merging until the pedal is floored, then it lurches. No codes, and the dealer couldn't reproduce it. One owner said the same thing on a 2021 PowerBoost stopped after replacing the 12V battery under the rear seat. Another said it's a transmission issue, reproducible at about 8 mph in 2nd gear, and linked a 24-page forum thread where only new transmissions solved it.
• In 21 PowerBoost (21k miles) my hybrid confidence is gone…Anyone receive goodwill or trade assistance from Ford Corporate? on Reddit r/f150, a 2021 PowerBoost XLT with 21,000 miles had five 'Stop Safely Now' events and was towed once. The dealer did an axle bolt recall and replaced the 12V battery but couldn't find a cause. Code P0AA6 was stored. Another owner replaced both 12V batteries and still had a dead truck with Stop Safely Now after a BMS reset.

Quick tip

Test the rear-seat battery first. It's cheap and often missed. If that doesn't fix it, document everything and push Ford.

Vehicle focus: Ford F-150 PowerBoost (3.5L full hybrid), 2021-2024.

Safety / mechanic note

Losing power in traffic is a crash risk, and P0AA6 involves high voltage. A plug-in hybrid's high-voltage system can stay live with the car off. Leave the orange cables and the big battery to a trained hybrid technician. Verify with a mechanic.