P0A7A The generator inverter is not performing as expected, or its fail signal looks wrong

Generator inverter performance

P0A7A in short

P0A7A means the generator inverter is not performing as expected, or its fail signal does not match what the hybrid computer sees. Toyota bulletins cover it on Prius, Camry, Avalon and RAV4 hybrids, and the fix ranges from an inverter repair to a bulletin procedure. Get it checked soon; stop if power drops. The inverter is high-voltage.

On a hybrid, the generator is an electric machine that makes power and starts the engine, and its inverter switches the high-voltage current for it. The inverter sends a fail signal to the motor control computer when it detects a problem, and the computer checks that signal against the inverter's real state. P0A7A sets when they do not agree.

Toyota and Lexus bulletins T-SB-0142-16 and L-SB-0087-16 cover 2012-2016 Avalon, Camry and RAV4 hybrids and 2013-2016 ES, GS and NX hybrids with P0A7A and information code 122, which names the generator inverter fail signal. Toyota's TSB001123 and program 23TE02 cover 2010-2017 Prius and Prius v, where a failing power module inside the inverter assembly sets P0A7A and/or P0A78.

On the 2022-2023 Mazda3 and CX-30 with a mild hybrid starter generator, Mazda's bulletin says P0A7A can come from over-sensitive overcurrent detection logic and is fixed with software. That is a different system from Toyota's full hybrid.

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

Most likely causes

  1. Failing power module in the inverter assembly (Prius, Prius v)

    Supported by vehicle data
    Why it ranks here
    Toyota bulletin TSB001123 names a malfunction in the inverter assembly with converter for P0A7A and/or P0A78 on 2010-2017 Prius and Prius v, and customer program 23TE02 covers the power module.
    What would change this
    Rises on a covered Prius or Prius v, or if P0A78 is stored too. Falls if the VIN is outside the program.
    How to test the hybrid drive motor

  2. Generator inverter fail signal fault, information code 122 (Avalon, Camry, RAV4, ES, GS, NX hybrids)

    Supported by vehicle data
    Why it ranks here
    Toyota and Lexus bulletins apply only when information code 122 is present with P0A7A and give a repair procedure for it; we did not read the bulletin procedure itself.
    What would change this
    Rises if the dealer reads information code 122 on a listed model. Falls if another information code is shown.

  3. Starter generator control software (Mazda3, CX-30 mild hybrid)

    Supported by vehicle data
    Why it ranks here
    Mazda bulletin 01-004-25 says over-sensitive overcurrent detection logic can store P0A7A:00 with P1BC5:00 on 2022-2023 Mazda3 and CX-30, fixed by an ISG software update.
    What would change this
    Rises on those Mazda models with both codes stored. Falls if the software is already updated.

  4. Other inverter or high-voltage fault

    Possible — needs testing
    Why it ranks here
    Complaints on a 2007 Highlander Hybrid and a 2008 Escape store P0A7A with a defective inverter and a transmission diagnosis, so other models can have a hardware fault outside the bulletins above.
    What would change this
    Rises if no bulletin applies and the inverter fails the maker's tests. Falls if a bulletin fix 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 with a scan tool and note any dashboard messages. Do not open or unplug anything in the hybrid system.

    Low riskTool: OBD-II scan tool

  2. Give the VIN to a dealer and ask for the information code, open bulletins and any customer program for the inverter.

    Low riskTool: VIN lookup at a dealer

  3. Have a dealer or hybrid-trained technician run the inverter and generator diagnostics from the maker's 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 with hybrid or battery warnings
  • Brake or stability control warnings Gets more serious: stop and have it checked.
  • Stop Safely message or loss of power while driving Gets more serious: stop and have it checked.
  • Hybrid system will not start

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

  • Inverter assembly with converter (Toyota):High-voltage part. Check bulletin TSB001123 and customer program 23TE02 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-0142-16Status unverified

    P0A7A with information code 122 on Avalon, Camry and RAV4 hybrids

    2012–2016avalon, camry, rav4 · issued · NHTSA 10132644

    Applies only when information code 122 (generator inverter fail signal detection) is present; follow the bulletin procedure. A 2019 revision updates the warranty section.

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

  • TSB001123Status unverified

    Inverter assembly repair for P0A7A and/or P0A78

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

    Identifies which components inside the inverter assembly with converter 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 under a class action settlement.

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

  • 02505Status unverified

    MIL on with P0A60, P0A63, P0A72, P0A78 or P0A7A

    2004–2005prius · issued · NHTSA 10015880

    Title-level summary only: lists P0A7A among codes for a lit warning lamp on the 2004-2005 Prius.

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

Lexus

  • L-SB-0087-16Status unverified

    P0A7A with information code 122 on ES, GS and NX hybrids

    2013–2016es, gs, nx · issued · NHTSA 10132643

    Same condition and condition for use as Toyota T-SB-0142-16.

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

Mazda

  • 01-004-25Status unverified

    ISG control software for P0A7A:00 and P1BC5:00

    2022–2023mazda3, cx-30 · issued · NHTSA 11019081

    Updates the integrated starter generator software to correct overcurrent detection thresholds that set the codes.

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

  • P0A78The inverter that powers hybrid drive motor A is not performing as expected

    Shares causes Supported by vehicle data

    Toyota's TSB001123 and program 23TE02 treat P0A7A and/or P0A78 as signs of the same inverter assembly failure on Prius and Prius v.

All Hybrid and electric drive codes

P0A7A questions

Is it safe to drive with P0A7A?

Only to get it checked, and only if it drives normally. If a Stop Safely message appears, the brake or stability warnings light, or power drops, stop somewhere safe and arrange a tow.

Can I fix P0A7A 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?

Possibly. Toyota customer program 23TE02 covers the power module on 2010-2017 Prius and Prius v. Give the VIN to a dealer to check.

Sources and review

  1. T-SB-0142-16: P0A7A with information code 122 on Avalon, Camry and RAV4 hybrids — Toyota Motor Sales
  2. TSB001123: P0A7A and/or P0A78, inverter assembly with converter — Toyota Motor Sales
  3. Fault code P0A7A (sub code 519) — TAT scan data library
  4. NHTSA complaint ODI 1676928: 2008 Ford Escape — NHTSA Office of Defects Investigation
  5. NHTSA complaint ODI 893121: 2007 Toyota Highlander Hybrid — NHTSA Office of Defects Investigation
  6. 23TE02: Customer Confidence Program for the intelligent power module — Toyota Motor Sales
  7. L-SB-0087-16: P0A7A with information code 122 on Lexus hybrids — Lexus
  8. 01-004-25: P0A7A with integrated starter generator software — Mazda North American Operations
Last reviewed
Written by
Saurabh K.
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