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.