Diagnostic Trouble Code
P0AFD
Hybrid Battery Pack Temperature Too Low
Technical Description P0AFD
Hybrid Battery Pack Temperature Too Low
Severity Level P0AFD
Insufficient battery pack or battery cell temperature and a stored code P0AFD could result in deactivation of the electric propulsion system. The P0AFD should be classified as severe and the conditions which contributed to its storage should be addressed with urgency.
What Does This Mean P0AFD?
This is a generic diagnostic trouble code (DTC) and applies to many OBD-II vehicles (1996-newer). That may include but is not limited to vehicles from Toyota, Honda, Ford, Subaru, etc. Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration.
If your hybrid vehicle (HV) has stored a code P0AFD, it means that the powertrain control module (PCM) has detected a degree of temperature (in or near) the vehicles high-voltage battery pack which is lower than the minimum allowable parameter. This code should be exhibited in hybrid vehicles, exclusively.
Composed of eight (1.2-volt) cells, arranged in series, the HV (nickel metal-hydride) battery is one of twenty-eight that make up the HV high-voltage battery pack.
The the high-voltage battery pack 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 pack condition are among the functions monitored and calculated by the HVBMS.
High voltage hybrid battery packs are wired in series with busbar connectors and sections of high voltage cable. Usually, each individual cell is outfitted with an integrated ammeter/temperature sensor. The HVBMS receives input data from each cell in order to monitor individual temperature and resistance levels.
If the HVBMS provides the PCM with an input signal that indicates insufficient battery pack or battery cell temperature, a code P0AFD will be stored and a malfunction indicator lamp may be illuminated. Most vehicle applications will require multiple ignition cycles (with a failure) before the MIL is illuminated.
If your hybrid vehicle (HV) has stored a code P0AFD, it means that the powertrain control module (PCM) has detected a degree of temperature (in or near) the vehicles high-voltage battery pack which is lower than the minimum allowable parameter. This code should be exhibited in hybrid vehicles, exclusively.
Composed of eight (1.2-volt) cells, arranged in series, the HV (nickel metal-hydride) battery is one of twenty-eight that make up the HV high-voltage battery pack.
The the high-voltage battery pack 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 pack condition are among the functions monitored and calculated by the HVBMS.
High voltage hybrid battery packs are wired in series with busbar connectors and sections of high voltage cable. Usually, each individual cell is outfitted with an integrated ammeter/temperature sensor. The HVBMS receives input data from each cell in order to monitor individual temperature and resistance levels.
If the HVBMS provides the PCM with an input signal that indicates insufficient battery pack or battery cell temperature, a code P0AFD will be stored and a malfunction indicator lamp may be illuminated. Most vehicle applications will require multiple ignition cycles (with a failure) before the MIL is illuminated.
Symptoms P0AFD
1
Diminished vehicle performance
2
Decreased fuel efficiency
3
Other HV battery related codes
4
Electric propulsion system deactivation
Possible Causes P0AFD
1
Defective HV battery, cell, or battery pack
2
Loose, broken, or corroded busbar connectors or cables
3
HVBMS sensor failure
4
Controller programming error
Solutions & Repair Steps P0AFD
The high-voltage battery should serviced by qualified personnel only.
I would gain access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of HV battery system diagnostic information before attempting to diagnose a code P0AFD.
I would begin my diagnosis with a visual inspection of the HV battery pack and all circuitry; focusing on signs of corrosion, damage, or other apparent open circuits. I would remove corrosion and repair (or replace) defective circuitry as required. Before performing any battery load testing, make sure that there are no corrosion issues present on the battery pack and that all connections are secure.
My next step would be connecting the scanner to the vehicle diagnostic connector and retrieving all stored codes and pertinent freeze frame data. I would record this information before clearing the codes and test driving the vehicle until the PCM either enters readiness mode or the code is reset.
The code is intermittent and may be much more difficult to diagnose if the PCM enters readiness mode (no codes stored) at this point.
If the P0AFD is reset, use the scanner to observe HV battery temperature data, If inconsistencies, between battery temperature and ambient temperature are observed, address these areas using your DVOM and the appropriate diagnostic information.
Testing procedures and specifications for the HV battery pack can be found in your source of HV information. Component location diagrams, wiring diagrams, connector face views, and connector pinout charts will be necessary in arriving at a correct diagnosis. Use the DVOM to test each individual temperature sensors (following manufacturer testing specifications and procedures). Sensors which do not comply with manufacturer’s specs should be considered defective.
I would gain access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of HV battery system diagnostic information before attempting to diagnose a code P0AFD.
I would begin my diagnosis with a visual inspection of the HV battery pack and all circuitry; focusing on signs of corrosion, damage, or other apparent open circuits. I would remove corrosion and repair (or replace) defective circuitry as required. Before performing any battery load testing, make sure that there are no corrosion issues present on the battery pack and that all connections are secure.
My next step would be connecting the scanner to the vehicle diagnostic connector and retrieving all stored codes and pertinent freeze frame data. I would record this information before clearing the codes and test driving the vehicle until the PCM either enters readiness mode or the code is reset.
The code is intermittent and may be much more difficult to diagnose if the PCM enters readiness mode (no codes stored) at this point.
If the P0AFD is reset, use the scanner to observe HV battery temperature data, If inconsistencies, between battery temperature and ambient temperature are observed, address these areas using your DVOM and the appropriate diagnostic information.
Testing procedures and specifications for the HV battery pack can be found in your source of HV information. Component location diagrams, wiring diagrams, connector face views, and connector pinout charts will be necessary in arriving at a correct diagnosis. Use the DVOM to test each individual temperature sensors (following manufacturer testing specifications and procedures). Sensors which do not comply with manufacturer’s specs should be considered defective.