P0A78 The inverter that powers hybrid drive motor A is not performing as expected

Drive Motor A Inverter Performance

P0A78 in short

P0A78 means the inverter that drives hybrid motor A is not performing as expected. Bulletins point to hybrid software on the Chrysler Pacifica Plug-in Hybrid and to inverter failures on some Prius, Civic Hybrid and Wrangler 4xe models. Get it checked soon, and stop if power drops. The inverter is high-voltage and not DIY.

A hybrid's inverter turns the high-voltage battery's direct current into the alternating current that runs the electric drive motors. P0A78 sets when the hybrid control system sees the inverter for motor A not performing as commanded.

On the Chrysler Pacifica Plug-in Hybrid, Chrysler bulletins for 2017 and 2022–2024 models call for reprogramming the hybrid control processors, and a 2019–2025 bulletin says to check for those updates before ordering a power inverter module. They mention a "Vehicle is shutting down in two minutes" warning; the van can usually restart on the next key cycle. On the 2021 Wrangler 4xe, Jeep's bulletin replaces the power inverter module.

On the 2010–2015 Prius and 2012–2017 Prius v, Toyota ties P0A78 and P0A7A to a failing power module inside the inverter and covers it under a customer confidence program. Honda extended coverage on the 2012–2015 Civic Hybrid and 2013 Acura ILX Hybrid for a solder joint failure in the motor inverter. On the 2014–2016 Subaru XV Crosstrek Hybrid, an engine computer update addresses this code.

The inverter is part of the high-voltage system. The orange cables and connectors are not for owners to touch or probe. Diagnosis belongs with a dealer or a hybrid-trained technician.

Most likely causes

  1. Hybrid control processor software (Pacifica Plug-in Hybrid)

    Supported by vehicle data
    Why it ranks here
    Four Chrysler bulletins list P0A78 with a reprogram of the hybrid control processors, and Chrysler's bulletin 9100801 says to check those updates before ordering an inverter.
    What would change this
    Rises if the updates are outstanding for the VIN. Falls if the latest software is installed and the code returns.

  2. Failed inverter or power module inside it

    Supported by vehicle data
    Why it ranks here
    Toyota, Honda, Acura and Jeep bulletins each tie P0A78 to a hardware failure inside the inverter on specific models, some with extended coverage.
    What would change this
    Rises on the covered Prius, Civic Hybrid, ILX Hybrid or Wrangler 4xe models, or if the code returns after software updates. Falls if a software update clears it for good.

  3. Engine computer software (Subaru XV Crosstrek Hybrid)

    Supported by vehicle data
    Why it ranks here
    Subaru's bulletin for the 2014–2016 XV Crosstrek Hybrid reprograms the engine computer for P0A78 to control motor current better.
    What would change this
    Applies only to that model. Rises if the update has not been done.

  4. Other high-voltage system fault (motor, wiring or cooling)

    Possible — needs testing
    Why it ranks here
    The code reports how the inverter is performing, and that can be affected by other parts of the drive system. We found no bulletin naming a specific cause outside the models above.
    What would change this
    Rises if the inverter and software check out. Falls if a covered cause above is confirmed.

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 with a scan tool and write down any dashboard messages. Do not open or unplug anything under the hood.

    Low riskTool: OBD-II scan tool

    • IfP0A78 is stored on a Pacifica Plug-in Hybrid, Wrangler 4xe, Prius, Prius v, Civic Hybrid, ILX Hybrid or XV Crosstrek Hybrid

      It meansA maker bulletin covers this code on that model.

      Go to step 2

    • IfThe vehicle is another hybrid

      It meansWe found no bulletin; it needs the maker's diagnosis.

      Go to step 3

  2. Give the VIN to a dealer and ask which software updates, warranty extensions or customer programs for the inverter are open.

    Low riskTool: VIN lookup at a dealer

  3. Have a dealer or hybrid-trained technician run the inverter diagnostics in the service information.

    Best left to a shopTool: factory scan tool and high-voltage safety equipment

    Warning:High voltage: the battery pack, inverter, motors and orange cables carry hundreds of volts that can kill. Do not unplug, probe or touch them. This work needs a hybrid-trained technician who makes the system safe first.

Symptoms

  • Check engine light and hybrid system warnings
  • Electric or hybrid mode not working; engine-only operation
  • Vehicle enters fail-safe mode with reduced power Gets more serious: stop and have it checked.
  • "Stop Safely" or "Vehicle is shutting down" message Gets more serious: stop and have it checked.
  • Loss of power while driving Gets more serious: stop and have it checked.

Compare with: Check engine light with loss of power

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

  • Power inverter module:High-voltage part. Check software updates and the maker's extended coverage for your VIN before paying; Chrysler says to rule out software before ordering one. 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

Chrysler

  • 2017–2025 · Pacifica

    Supported by vehicle data

    On the Pacifica Plug-in Hybrid, Chrysler bulletins list P0A78 with hybrid control processor updates and a shut-down warning, and owners report losing power in traffic. Bulletin status is not verified, so this is labelled vehicle data.

  • 08-208-24Status unverified

    HCP and AHCP updates for P0A78/P0A79

    2023pacifica · issued · NHTSA 11008206

    Mentions a "Vehicle is shutting down in two minutes" message; restarts on next key cycle.

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

  • 08-209-24Status unverified

    HCP and AHCP updates for P0A78/P0A79

    2024pacifica · issued · NHTSA 11008207

    Same as 08-208-24 for 2024 models.

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

  • 08-218-24Status unverified

    HCP and AHCP/PIM updates for P0A78 and P0E15

    2022pacifica · issued · NHTSA 11008750

    Shut-down message, electric mode not working, reduced cabin heat.

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

  • 08-044-17Status unverified

    HCP and AHCP reprogramming

    2017pacifica · issued · NHTSA 10224727

    Lists P0A78 with P0A79, P0A3F and other codes.

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

  • 9100801Status unverified

    Check hybrid control processor flashes before ordering a power inverter module

    2019–2025pacifica, voyager · issued · NHTSA 11031685

    For P0A78 and related motor and inverter codes, do the HCP/AHCP flashes from active bulletins before ordering a power inverter module.

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

Jeep

  • 2021 · Wrangler

    Supported by vehicle data

    On the 2021 Wrangler 4xe, Jeep's bulletin replaces the power inverter module for P0A78; the vehicle runs on the engine only until repaired.

  • 08-178-23Status unverified

    Power inverter module replacement for P0A78/P0A79

    2021wrangler · issued · NHTSA 10242816

    Engine-only operation with no electric mode; replace the power inverter module.

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

Toyota

  • 2010–2015 · Prius

    Supported by vehicle data

    Toyota ties P0A78 and P0A7A to the power module inside the inverter and covers it under program 23TE02. Ask a dealer to check the VIN.

  • 2012–2017 · Prius V

    Supported by vehicle data

    Same inverter bulletin and program 23TE02 as the Prius.

  • TSB-0011-23Status unverified

    Inverter assembly repair for P0A7A and/or P0A78

    2010–2017prius, prius-v · issued · NHTSA 10235229

    Identifies which components inside the inverter assembly to replace.

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

  • 23TE02Status unverified

    Customer Confidence Program: intelligent power module

    2010–2017prius, prius-v · issued · NHTSA 10240055

    Covers power module failure inside the inverter with P0A7A and/or P0A78; warning lamps and fail-safe mode.

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

Honda

  • 2012–2015 · Civic

    Supported by vehicle data

    Civic Hybrid only: Honda extended motor inverter coverage to 15 years or 150,000 miles for a solder joint failure that sets P0A78.

  • A20-030Status unverified

    Motor power inverter warranty extension (Civic Hybrid)

    2012–2015civic · issued · NHTSA 10184658

    Solder joint failure in the motor inverter; coverage extended to 15 years or 150,000 miles.

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

Acura

  • B20-021Status unverified

    Motor power inverter warranty extension (ILX Hybrid)

    2013ilx · issued · NHTSA 10184664

    Same as Honda A20-030.

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

Subaru

  • 2014–2016 · XV CrossTrek

    Supported by vehicle data

    XV Crosstrek Hybrid only: an engine computer update addresses P0A78; hybrid functions are off while it is stored.

  • 11-180-18Status unverified

    ECM reprogramming for P0A78 and P1C2A

    2014–2016xv-crosstrek · issued · NHTSA 10141494

    Hybrid functions inoperative while the code is stored; update adds motor current protection.

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

  • P0A43Hybrid drive motor A position sensor signal cutting in and out

    Shares causes Supported by vehicle data

    Chrysler's bulletin 9100801 lists both codes on the 2019–2025 Pacifica and says to check hybrid control processor updates before ordering an inverter.

  • P0E15The heater that warms the hybrid battery's coolant is not doing what the hybrid computer commands

    Shares causes Supported by vehicle data

    Chrysler's bulletin 08-218-24 for the 2022 Pacifica Plug-in Hybrid fixes both codes with the same hybrid control processor updates.

All Hybrid and electric drive codes

P0A78 questions

Is it safe to drive with P0A78?

Only to get it checked, and only if it drives normally. If a "Stop Safely" or shut-down message appears or power drops, stop somewhere safe and have it towed.

Can I fix P0A78 myself?

No. The inverter is part of the high-voltage system and needs a dealer or hybrid-trained technician.

Is the inverter covered on my Prius or Civic Hybrid?

Possibly. Toyota's program 23TE02 covers the inverter power module on 2010–2017 Prius and Prius v, and Honda extended inverter coverage on the 2012–2015 Civic Hybrid. Give the VIN to a dealer to check.

Sources and review

  1. HCP and AHCP updates for P0A78/P0A79, 2023 Pacifica Plug-in Hybrid (bulletin 08-208-24) — FCA US LLC / NHTSA ,
  2. Customer Confidence Program 23TE02: intelligent power module coverage, Prius and Prius v — Toyota Motor Sales / NHTSA ,
  3. ECM reprogramming for P0A78 and P1C2A, XV Crosstrek Hybrid (bulletin 11-180-18) — Subaru of America / NHTSA ,
  4. Owner complaints: 2021–2024 Chrysler Pacifica Plug-in Hybrid shutting down with P0A78 — NHTSA Office of Defects Investigation
  5. HCP and AHCP updates for P0A78/P0A79, 2024 Pacifica Plug-in Hybrid (bulletin 08-209-24) — FCA US LLC / NHTSA ,
  6. HCP and AHCP/PIM software updates for P0A78 and P0E15, 2022 Pacifica Plug-in Hybrid (bulletin 08-218-24) — FCA US LLC / NHTSA ,
  7. HCP and AHCP reprogramming, 2017 Pacifica Plug-in Hybrid (bulletin 08-044-17) — FCA US LLC / NHTSA ,
  8. Check hybrid control processor flashes before ordering a power inverter module (bulletin 9100801) — FCA US LLC / NHTSA ,
  9. Inverter assembly repair for P0A7A and/or P0A78, 2010–2015 Prius and 2012–2017 Prius v (TSB-0011-23) — Toyota Motor Sales / NHTSA ,
  10. Motor power inverter warranty extension, 2012–2015 Civic Hybrid (bulletin A20-030) — American Honda Motor Co. / NHTSA ,
  11. Motor power inverter warranty extension, 2013 ILX Hybrid (bulletin B20-021) — American Honda Motor Co. / NHTSA ,
  12. Power inverter module replacement for P0A78/P0A79, 2021 Jeep Wrangler 4xe (bulletin 08-178-23) — FCA US LLC / NHTSA ,
  13. Maintenance and Safety of Electric Vehicles — Alternative Fuels Data Center, U.S. Department of Energy
Last reviewed
Written by
Saurabh K.
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