P0A0F The hybrid computer commanded the gasoline engine to start and the engine did not start

Engine failed to start (hybrid)

P0A0F in short

P0A0F means the hybrid control computer told the gasoline engine to start and it did not. Toyota and Lexus bulletins tie it on the Prius, Prius v and CT 200h to a loose purge valve line or, in cold weather, the intake manifold, and Kia ties it on the Niro to a harness. Stop if power drops while driving.

On a hybrid the engine starts and stops as the computer decides, so a failed start can happen anywhere. P0A0F sets when the computer commands a start and the engine does not come up as expected. Toyota names it "Engine Failed to Start" in its bulletins.

Toyota T-SB-0041-15 covers 2010-2013 Prius and 2012-2013 Prius v with P0A0F caused by the purge VSV/PCV line separating from the throttle body housing, and replaces the valve and reprograms the ECM; Lexus L-SB-0019-15 covers the 2011-2013 CT 200h. T-SB-0103-12 covers P2111 and P0A0F in cold weather and an improved intake manifold. Kia PS554 says a shorted A/C pressure transducer harness on 2017 Niro can be behind P0A0F. We read only the bulletin summaries.

Owner complaints show P0A0F with P3190 on a 2010 Prius that lost power on a freeway, and with P261F on a 2016 Sonata Hybrid where the dealer replaced the ignition coils and the problem returned.

The hybrid system is high-voltage. Do not open or unplug orange cables. Diagnosis belongs with a dealer or a hybrid-trained technician.

Most likely causes

  1. Purge VSV/PCV line separated from the throttle body (Prius, Prius v, CT 200h)

    Supported by vehicle data
    Why it ranks here
    Toyota T-SB-0041-15 and Lexus L-SB-0019-15 name this for P0A0F on 2010-2013 Prius, 2012-2013 Prius v and 2011-2013 CT 200h and replace the purge VSV and reprogram the ECM.
    What would change this
    Rises on a covered Prius, Prius v or CT 200h, especially with P3190, P3191 or P0171. Falls if the line is intact.

  2. Intake manifold in cold weather (Prius family)

    Supported by vehicle data
    Why it ranks here
    Toyota T-SB-0103-12 applies when P2111 and P0A0F set below about -5 C on 2ZR-FXE engines and uses an improved intake manifold.
    What would change this
    Rises with P2111 and cold ambient temperatures. Falls in warm weather.

  3. Shorted A/C pressure transducer harness (2017 Niro)

    Supported by vehicle data
    Why it ranks here
    Kia PS554 says the harness can short against the idler pulley on Niro built before August 21, 2017, with P0A0F, P040400 and/or poor A/C operation.
    What would change this
    Rises on an early 2017 Niro with A/C problems. Falls if the harness is clean and secure.

  4. Other engine start fault (ignition, fuel or air)

    Possible — needs testing
    Why it ranks here
    A 2016 Sonata Hybrid kept setting P0A0F with P261F after ignition coils were replaced, so other causes remain possible; no bulletin in our sources covers it.
    What would change this
    Rises if no bulletin applies. Falls if a maker repair clears the code.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all stored codes and freeze-frame data with a scan tool and note every dashboard message. Do not open or unplug anything.

    Low riskTool: OBD-II scan tool

    • IfP0A0F is stored with P3190, P3191, P2111 or P0171 on a Prius, Prius v or CT 200h

      It meansToyota bulletins may apply.

      Go to step 2

    • IfIt is stored on a Niro with A/C trouble

      It meansKia PS554 may apply.

      Go to step 2

    • IfIt is any other vehicle

      It meansThe maker diagnosis decides.

      Go to step 3

  2. Give the VIN to a dealer and ask for open bulletins and recalls for engine start faults, the purge valve line and the intake manifold.

    Low riskTool: VIN lookup at a dealer

  3. Have a dealer or hybrid-trained technician look for the reason the engine did not start, using the maker service information.

    Best left to a shopTool: factory scan tool

    Warning:Hot exhaust and a car that can start the engine on its own: the engine can start without warning while the system is in Ready mode, and the hybrid system is high-voltage. Do not work under the hood in Ready mode.

Symptoms

  • Check engine or check hybrid system warning
  • Loss of power or stall while driving Gets more serious: stop and have it checked.
  • Engine runs rough then cuts out
  • Poor A/C operation (Niro)

How to fix

This is a safety-critical system, so we explain the code but don't give repair steps. Have it inspected by a qualified technician.

Parts and cost context

  • Purge VSV and throttle body line (Prius family) or intake manifold:Check Toyota T-SB-0041-15 and T-SB-0103-12 for your VIN before paying. Labor varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Toyota

  • T-SB-0041-15Status unverified

    P0A0F from purge VSV/PCV line separation

    2010–2013prius, prius-v · issued · NHTSA 10111144

    Replace the purge VSV and reprogram the ECM.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • T-SB-0103-12 RevStatus unverified

    P2111 and P0A0F in cold weather

    2010–2016prius, prius-v · issued · NHTSA 10133729

    Improved intake manifold assembly.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Lexus

  • L-SB-0019-15Status unverified

    P0A0F from purge VSV/PCV line separation (CT 200h)

    2011–2013ct · issued · NHTSA 10111152

    Same condition and repair as Toyota T-SB-0041-15.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Kia

  • 2017–2018 · Niro

    Supported by vehicle data

    Kia says a shorted A/C pressure transducer harness can be behind P0A0F on early 2017 builds.

  • PS554Status unverified

    P0A0F and P040400 and/or improper A/C operation

    2017–2018niro · issued · NHTSA 10136620

    Check for a shorted A/C pressure transducer harness; repair and re-route it.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Hyundai

  • 2016 · Sonata

    Possible — needs testing

    Sonata Hybrid: owner reports P0A0F with P261F; ignition coils were replaced and it returned. No bulletin found.

  • P3190Poor engine power on Toyota and Lexus hybrids

    Shares causes Supported by vehicle data

    Toyota bulletins list P0A0F with P3190 (poor engine power) and P3191 (engine does not start) for the same engine start faults.

  • P2111The engine computer commanded the electronic throttle to close further but saw it stay more open than expected

    Shares causes Supported by vehicle data

    Toyota T-SB-0103-12 lists P2111 with P0A0F in cold weather.

All Hybrid and electric drive codes

P0A0F questions

Is it safe to drive with P0A0F?

Only to get it checked, and only if it drives normally. If the car loses power or stalls while driving, stop somewhere safe and arrange a tow.

Is P0A0F always a bad engine?

No. Toyota bulletins trace it on some Prius, Prius v and CT 200h cars to a loose purge valve line or a cold-weather intake manifold issue, so ask a dealer to check bulletins first.

Sources and review

  1. T-SB-0041-15: P0A0F (Engine Failed to Start) from a purge VSV/PCV line — Toyota Motor Sales ,
  2. NHTSA complaint ODI 10488024: 2010 Toyota Prius — NHTSA Office of Defects Investigation
  3. NHTSA complaint ODI 11061129: 2016 Hyundai Sonata Hybrid — NHTSA Office of Defects Investigation
  4. P0A0F Engine Failed to Start — Troublecodes.net
  5. T-SB-0103-12 Rev: P2111 and P0A0F in cold weather — Toyota Motor Sales ,
  6. PS554: P0A0F and P040400 and/or improper A/C operation (Niro) — Kia America ,
  7. Fault code P0A0F — TAT scan data library
  8. NHTSA complaint ODI 11666693: 2013 Toyota Prius — NHTSA Office of Defects Investigation
Last reviewed
Written by
Saurabh K.
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