P0A7A Possible Causes

• Faulty inverter with converter assembly
• Inverter with converter assembly harness open or shorted
• Inverter with converter assembly circuit poor electrical connection

What Does It Mean?

How to Fix Code P0A7A

Check the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, ejected, or corroded connector pins.

P0A7A Possible Symptoms

Illuminated engine light (or service engine soon warning light)

P0A7A Meaning

The inverter converts the high voltage DC from the HV battery and the AC from MG1/MG2. The inverter contains a three-phase bridge circuit, consisting of 6 power transistors each for MG1 and MG2, to convert DC and three-phase AC.
The HV control ECU controls the operation of the power transistors.

The inverter transmits the necessary information for control, such as current and voltage, to the HV control ECU.
The motor inverter current sensors detect the current flowing through the V and W phase cables between the inverter and MG1/MG2. The inverter transmits the necessary information for control, such as current and voltage, to the HV control ECU.
The HV control ECU monitors the inverter current sensors to detect a malfunction in the sensor system.

P0A7B Possible Causes

• Faulty battery energy control module
• Battery energy control module harness is open or shorted
• Poor electrical connection in battery energy control module circuit

What Does It Mean?

How to Fix Code P0A7B

Check the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P0A7B Possible Symptoms

Check engine light illuminated (or service engine soon warning light)

P0A7B Meaning

The engine control module (ECM) monitors the battery energy control module. The ECM sets the OBDII code when the battery energy control module does not meet factory specifications.
OBDII Code P0A7B – MIL illumination required for battery energy control module

P0A7C Possible Causes

• Faulty motor electronics
• Motor electronics harness is open or shorted
• Poor electrical connection of motor electronics circuit

What Does It Mean?

How to Fix Code P0A7C

Check the “possible causes” listed above. Visually inspect the wiring harness and related connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P0A7C Possible Symptoms

Engine light on (or service engine soon warning light)

P0A7C Meaning

The engine control module (ECM) monitors the motor electronics. The ECM sets the OBDII code when the motor electronics do not meet factory specifications.
OBDII Code P0A7C – Motor Electronics Overheating

What does it mean?

This is a generic diagnostic trouble code (DTC) and applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from Toyota (Prius, Camry), Lexus, Fisker, Ford, Hyundai, GM, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

If your hybrid vehicle (HV) has stored a P0A7D code, it means that the powertrain control module (PCM) has detected an insufficient state of charge regarding the high-voltage battery. This code should only be stored in hybrid vehicles.

Typically, the HV battery (nickel-metal hydride) is composed of eight cells (1.2 volts) arranged in series. Twenty-eight of these cells make up the HV battery. A hybrid vehicle battery management system (HVBMS) is responsible for regulating and monitoring the high-voltage battery. The HVBMS interacts with the PCM and other controllers as needed.

Individual cell resistance, battery voltage, and battery temperature are all factors considered by the HVBMS (and other controllers) when calculating the battery status and desired state of charge. Most hybrid vehicles use an HVBMS where each cell is equipped with an ammeter/temperature sensor. The HVBMS monitors data from each cell and compares individual voltage levels to determine if the battery is operating at the desired state of charge. Once the data is calculated, the appropriate controller reacts accordingly.

If the PCM detects an HVBMS voltage level insufficient for the conditions, a P0A7D code will be stored, and a malfunction indicator light (MIL) may illuminate. In some cases, multiple failure cycles will be required for the MIL to light up.

How severe is this DTC?

The stored P0A7D code and all other codes related to the HVBMS should be classified as severe and treated as such. The hybrid propulsion system may be disabled when this code is stored.

What are some of the symptoms of the code?

Symptoms of a P0A7D trouble code may include:

• Decreased energy efficiency
• Reduced overall performance
• Other codes related to the HV battery
• Electric propulsion system deactivation

What are some common causes of the code?

Causes of this code may include:

• Faulty HV battery, cell, or battery pack
• Faulty alternator, turbine, or generator
• HVBMS sensor failure
• HV battery fans not functioning properly
• Loose, broken, or corroded busbar connectors or cables

What are the troubleshooting steps for P0A7D?

If battery charging system codes are also present, diagnose and repair them before attempting to diagnose P0A7D.

You will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of HV battery system diagnostic information to accurately diagnose a P0A7D code.

Start with a visual inspection of the HV battery and all circuits. Look for signs of corrosion, damage, or open circuits. Remove corrosion and repair faulty components as needed.

Use the scanner to retrieve all stored codes and relevant freeze frame data. After recording this information, clear the codes and test the vehicle. If possible, test the vehicle until the PCM enters readiness mode or the code resets.

If P0A7D resets, use the scanner to observe HV battery charging data and battery state of charge. Obtain battery testing procedures and specifications from your HV information source. Locating component location diagrams, wiring schematics, connector face views, and appropriate connector pinout diagrams will help establish an accurate diagnosis.

If the battery is found to be faulty: Repairing the HV battery is a possibility but may not be reliable. The safest way to rectify a faulty HV battery is to replace it with an original equipment part, but this can be cost-prohibitive. If that is the case, consider a used HV battery.

If the battery meets functional specifications, test the appropriate HVBMS sensors (temperature and voltage) following the manufacturer’s testing specifications and procedures. This can be done using the DVOM. Replace sensors that do not meet the manufacturer’s specifications.

If all sensors appear to be functioning as expected, use the DVOM to test the resistance of individual cells. For cells showing an unacceptable degree of resistance, test the busbar connectors and cables using the DVOM.

• Faulty cells and batteries can be replaced, but total replacement of the HV battery pack is normally the most reliable solution
• A stored P0A7D code will not automatically disable the HV battery charging system, but the conditions that caused the code to be stored may disable it.
• If the HV in question has over 100,000 miles on the odometer, suspect an HV battery pack failure
• If the vehicle has less than 100 miles, a loose or corroded connection is likely your malfunction

What does it mean?

This is a generic diagnostic trouble code (DTC) and applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from Toyota, Honda, Ford, Subaru, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

If your hybrid vehicle (HV) has stored a P0A7E code, it means that the powertrain control module (PCM) has detected a temperature level (in or near) the vehicle’s high-voltage battery that exceeds the maximum allowable parameter. This code should be exclusively displayed in hybrid vehicles.

Composed of eight cells (1.2 volts), arranged in series, the HV battery (nickel-metal hydride) is one of the twenty-eight that make up the HV high-voltage battery pack.

The high-voltage battery is monitored by the hybrid vehicle battery management system (HVBMS), which also interacts with the PCM and other controllers. Battery temperature, cell resistance, battery charge level, and overall battery condition are among the functions monitored and calculated by the HVBMS.

High-voltage hybrid batteries are wired in series with busbar connectors and high-voltage cable sections. Usually, each individual cell is equipped with a built-in ammeter/temperature sensor. The HVBMS receives input data from each cell to monitor individual temperature and resistance levels.

If the HVBMS provides the PCM with an input signal indicating excessive battery or battery cell temperature, a P0A7E code will be stored, and a malfunction indicator light may illuminate. Most vehicle applications will require multiple ignition cycles (with a fault) before the MIL is illuminated.

How severe is this DTC?

Excessive battery or battery cell temperature and a stored P0A7E code can result in the electric propulsion system being disabled. P0A7E should be classified as severe, and the conditions that contributed to its storage should be addressed urgently.

What are some of the symptoms of the code?

Symptoms of a P0A7E fault code may include:

• Decreased vehicle performance
• Reduced energy efficiency
• Other HV battery-related codes
• Electric propulsion system deactivation

What are some common causes of the code?

Causes of this code may include:

• Faulty HV battery, cell, or battery pack
• Loose, broken, or corroded busbar connectors or cables
• HVBMS sensor failure
• HV battery fans not operating correctly
• Controller programming error

What are the troubleshooting steps for P0A7E?

The high-voltage battery should only be serviced by qualified personnel.

I would want access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of HV battery system diagnostic information before attempting to diagnose a P0A7E code.

I would start my diagnosis with a visual inspection of the HV battery and all circuits, focusing on signs of corrosion, damage, or other apparent open circuits. I would remove corrosion and repair (or replace) faulty circuits as needed. Before performing any battery load testing, ensure there is no corrosion issue on the battery and that all connections are secure.

My next step would be to connect the scanner to the vehicle’s diagnostic connector and retrieve all stored codes and relevant freeze frame data. I would want to record this information before clearing the codes and test driving the vehicle until the PCM enters readiness mode or the code resets.

The code is intermittent and may be much harder to diagnose if the PCM enters readiness mode (no stored codes) at this point.

If the P0A7E is reset, use the scanner to observe the HV battery temperature data. If inconsistencies between battery temperature and ambient temperature are observed, address these areas using your DVOM and appropriate diagnostic information.

HV battery pack testing procedures and specifications can be found in your HV information source. Component location diagrams, wiring schematics, connector face views, and connector pinout diagrams will be necessary to achieve a correct diagnosis. Use the DVOM to test each individual temperature sensor (following the manufacturer’s specifications and testing procedures). Sensors not meeting the manufacturer’s specifications should be considered faulty.

• Although a stored P0A7E code may not automatically disable the HV battery charging system, the conditions that caused the code to be stored may disable it
• If the HV in question has over 100,000 miles on the odometer, suspect an HV battery pack failure
• If the vehicle has less than 100 miles, a loose or corroded connection is likely the source of your malfunction

What Does It Mean?

This is a generic diagnostic trouble code (DTC) that applies to many OBD-II vehicles (1996 and newer). This may include, but is not limited to, vehicles from Honda (Accord, Civic, Insight), Toyota (Prius, Camry), Lexus, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

A stored P0A7F code in your hybrid vehicle (HV) means that the powertrain control module (PCM) has detected excessive resistance or an insufficient state of charge in the high-voltage battery. This code should only be stored in hybrid vehicles.

The HV battery (nickel-metal hydride) typically consists of eight cells (1.2 volts) arranged in series. Twenty-eight of these cells make up the HV battery.

The hybrid vehicle battery management system (HVBMS) is responsible for regulating and monitoring the high-voltage battery. The HVBMS interacts with the PCM and other controllers as needed. The PCM is powered by data from the HVBMS via the controller area network (CAN). Individual battery cell resistance, temperature, battery charge level, and overall battery condition are among the functions continuously monitored by the HVBMS.

High-voltage hybrid battery packs are configured from twenty-eight battery cells that are wired together using busbar connectors and high-voltage cable sections. Typically, each of the cells is equipped with an ammeter/temperature sensor. The HVBMS monitors data from each cell and compares individual resistance and temperature levels to determine the precise degree of battery deterioration.

If the HVBMS provides the PCM with an input signal indicating inconsistent battery or battery cell temperature and/or voltage (resistance), a P0A7F code will be logged, and a malfunction indicator light may illuminate. Many vehicles require multiple ignition cycles with a fault before the MIL is activated.

How Severe Is This DTC?

Battery deterioration and a stored P0A7F code could result in the electric propulsion system being disabled. P0A7F should be classified as severe, and the conditions that contributed to its storage should be addressed urgently.

What Are Some of the Symptoms of the Code?

Symptoms of a P0A7F fault code may include:

• Decreased vehicle performance
• Reduced energy efficiency
• Other HV battery-related codes
• Electric propulsion system deactivation

What Are Some Common Causes of the Code?

Causes of this code may include:

• Faulty HV battery, cell, or battery pack
• Loose, broken, or corroded busbar connectors or cables
• Faulty alternator, turbine, or generator
• HVBMS sensor failure
• HV battery fans not functioning properly

What Are the Troubleshooting Steps for P0A7F?

Diagnose and repair any battery charging system codes that are present before attempting to diagnose P0A7F.

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of HV battery system diagnostic information will be needed to properly diagnose a P0A7F code.

I would start my diagnosis with a visual inspection of the HV battery and all circuits. I would look for corrosion, damage, or open circuits. Remove corrosion and repair (or replace) faulty components as needed. Ensure no corrosion issues are present on the battery pack and that all connections are secure before testing the battery.

Next, I would connect the scanner to the vehicle’s diagnostic connector and retrieve all stored codes and relevant freeze frame data. I would record this information, clear the codes, and test the vehicle until the PCM enters readiness mode or the code resets.

If the PCM enters readiness mode (no stored codes), the code is intermittent and may be much more difficult to diagnose.

If the P0A7F resets, use the scanner to observe HV battery charge data, battery temperature data, and battery charge status data. If inconsistencies are detected, address these areas using your DVOM and appropriate diagnostic information.

Battery testing procedures and specifications can be found in your HV information source. Component location diagrams, wiring schematics, connector face views, and connector pinout diagrams will be essential for achieving a correct diagnosis.

If the battery proves to meet functional specifications, my next step would be to use the DVOM to test the HVBMS sensors (temperature and voltage—following the manufacturer’s testing specifications and procedures). Sensors not meeting the manufacturer’s specifications should be considered faulty.

I would also use the DVOM to test the individual resistance of the battery cells. Cells showing excessive resistance will require the busbar connectors and cables to be tested.

Remember that HV battery repair is a possibility but often proves unreliable. Replacing the HV battery

with an OEM component is the most reliable method to rectify a faulty battery situation but can be expensive. You may opt for a used HV battery if cost is an issue.

• A stored P0A7F code will not automatically disable the HV battery charging system, but the conditions that caused the code to be stored may disable it.
• If the HV in question has over 100,000 miles on the odometer, suspect an HV battery pack failure
• If the vehicle has less than 100 miles, a loose or corroded connection is likely the source of your malfunction

What does it mean?

This generic powertrain diagnostic trouble code (DTC) generally applies to many OBD-II hybrid electric vehicles. This may include, but is not limited to, vehicles from Toyota (Prius, Camry), Lexus, Fisker, Ford, Hyundai, GM, etc.

When a P0A80 code is stored, it means that the powertrain control module has detected a malfunction in the hybrid vehicle battery management system (HVBMS). This code indicates that a weak cell failure has occurred in the hybrid battery.

Hybrid vehicles (which do not require external charging) use nickel-metal hydride batteries. The battery packs are actually battery blocks (modules) that are wired together using connector sections or busbar cables. The typical HV battery consists of eight cells (1.2 volts) in series. Twenty-eight modules make up the typical HV battery.

The HVBMS regulates the battery’s charge level and monitors its condition. Individual cell resistance, battery voltage, and battery temperature are all factors considered by the HVBMS and PCM when determining the battery’s state and desired charge level.

Several ammeter sensors and temperature sensors are placed at strategic points throughout the HV battery assembly. In most cases, each cell is equipped with an ammeter/temperature sensor. These sensors provide the HVBMS with data from each cell. The HVBMS compares individual voltage signals to determine if inconsistencies are present and reacts accordingly. The HVBMS also provides the PCM with data, via the controller area network (CAN), regarding the battery’s charge level and battery status.

When the HVBMS provides the PCM with an input signal that reflects inconsistent battery or cell temperature and/or voltage (resistance), a P0A80 code will be stored and a malfunction indicator light may illuminate.

How severe is this DTC?

A P0A80 code indicates a serious malfunction in a major component of the hybrid powertrain vehicle. It should be addressed urgently.

What are some of the symptoms of the code?

Symptoms of a P0A80 fault code may include:

• Decreased energy efficiency
• Reduced overall performance
• Other HV battery-related codes
• Electric propulsion system deactivation

What are some common causes of the code?

Causes of this code may include:

• Faulty HV battery, cell, or battery block
• HVBMS sensor failure
• Excessive individual cell resistance
• Variations in cell voltage or temperature
• HV battery fans not operating correctly
• Loose, broken, or corroded connectors or busbar cables

What are the P0A80 troubleshooting steps?

NOTE: The high voltage battery should only be serviced by qualified personnel.

If the HV in question has more than 100,000 miles on the odometer, suspect an HV battery pack failure.

If the vehicle has less than 100,000 miles, a loose or corroded connection is likely the source of your malfunction. Repairing or refurbishing the HV battery block is a possibility, but either of these options may prove unreliable. The safest method to correct a faulty HV battery is replacement with a factory part. If the cost is prohibitive for the situation, consider a used HV battery.

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of HV battery diagnostic information will be needed to diagnose a P0A80 code. Use the scanner to observe HV battery charge data after obtaining test procedures and specifications from the HV information source. Component location diagrams, wiring schematics, connector face views, and connector pinout charts will be essential for reaching an accurate diagnosis.

Visually inspect the HV battery and all circuits for signs of corrosion or open circuits. Remove corrosion and repair faulty components as needed.

After retrieving all stored codes and relevant freeze frame data (connect the scanner to the vehicle’s diagnostic port), clear the codes and test the vehicle to see if the P0A80 resets. Test the vehicle until the PCM enters readiness mode or the code resets. If the code resets, use the scanner to identify the HV battery cells experiencing inconsistencies. Make a note of the cells and continue your diagnosis.

Using the freeze frame data (from the scanner), determine whether the condition that caused the P0A80 to be stored involved an open circuit, high cell/circuit resistance, or a temperature difference in the HV battery pack. Test the appropriate HVBMS sensors (temperature and voltage) following the manufacturer’s specifications and test procedures. Replace any sensors that do not meet the manufacturer’s specifications.

You can test individual cells for resistance using the DVOM. If the individual cells show an acceptable degree of resistance, use the DVOM to test the resistance in the connectors and busbar cables. Individual cells and batteries can be replaced, but

Replacing the HV battery pack may prove to be the most reliable solution.

A stored P0A80 code will not automatically disable the HV battery charging system, but the conditions that caused the code to be stored may disable it.

Error Code P0A81: Causes, Symptoms, and Solutions

1. Possible Causes

• Faulty battery cooling fan assembly
• Open or shorted circuit in the battery cooling fan assembly wiring
• Poor electrical connection in the battery cooling fan assembly circuit
• Faulty integration relay
• Faulty battery smart unit
• Power management control ECU

2. Possible Symptoms

• Check engine light on (or service engine soon warning light)

3. Meaning of Code P0A81

Cooling air flows from the intake located on the right side of the rear seat and moves through an intake duct to the battery blower, located on the right surface of the luggage compartment. Then, the cooling air passes through another intake duct connecting the battery blower assembly to the upper right surface of the HV battery assembly, and then flows into it.

The cooling air flows from top to bottom between the HV battery modules. Once the air has cooled the modules, it is discharged from the lower right surface of the HV battery assembly. The exhausted air passes through an exhaust duct located on the right surface of the luggage compartment and is then vented into the cabin as well as outside the vehicle.

The battery computer uses temperature sensors to detect the temperature of the HV battery assembly. Based on the results of this detection, the battery ECU controls the battery fan assembly. Thus, the battery blower assembly starts when the HV battery temperature reaches a predetermined threshold.

The speed of the battery cooling fan assembly is controlled by the power management ECU. Power to the fan is supplied when the FCTL terminal of the ECU activates the battery fan relay. The ECU sends control signals (SI) to the fan assembly to adjust its speed based on the HV battery temperature. Information about the voltage applied to the fan assembly (VM) is sent to the ECU as a monitoring signal.

4. How to Fix Code P0A81?

1. Check the possible causes mentioned above.
2. Visually inspect the wiring harness and associated connectors.
3. Look for damaged components.
4. Check connector pins for possible breaks, bends, dislodgement, or signs of corrosion.
5. Test the proper operation of the cooling fan and its control circuits.
6. Replace faulty components if necessary.

By following these steps, you can identify and correct the source of the P0A81 code to ensure the proper functioning of the HV battery cooling system.

P0A82 Possible Causes

• Quarter ventilation duct
• Quarter ventilation hose No. 2
• Quarter inner ventilation duct No. 2
• Inner fan duct
• Faulty battery fan assembly
• Faulty battery ECU

What Does It Mean?

How to Fix Code P0A82

Check the “Possible Causes” listed above. Visually inspect the wiring harness and related connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P0A82 Possible Symptoms

Check engine light illuminated (or service engine soon warning light)

P0A82 Meaning

Cooling air flows into the intake on the right side of the rear seat and moves through an intake duct to the battery blower on the right surface of the luggage compartment. Additionally, cooling air passes through an intake duct (which connects the battery blower assembly to the upper right surface of the HV battery assembly) and flows to the HV battery assembly.
Cooling air circulates from top to bottom between the HV battery modules. Once it has cooled the modules, it is discharged from the lower right surface of the HV battery assembly.
The exhausted air passes through an exhaust duct on the right surface of the luggage compartment and is discharged into the cabin as well as outside the vehicle.

The battery computer uses battery temperature sensors to detect the temperature of the HV battery assembly. Based on the results of this detection, the battery ECU controls the battery fan assembly. (Thus, the battery blower assembly starts when the HV battery temperature reaches a predetermined level.)

The speed of the battery cooling fan assembly is controlled by the power management control ECU. Power to the battery cooling fan assembly is supplied when the FCTL terminal of the power management control ECU activates the battery fan relay. The power management control ECU sends control signals (SI) to the battery cooling fan assembly to achieve the fan speed corresponding to the HV battery temperature. Information about the voltage applied to the battery cooling fan assembly (VM) is sent to the power management control ECU as a monitor signal using serial communication via the
OBDII Code P0A82 – Hybrid Battery Pack Cooling Fan 1 Performance/Stuck