DTC Advanced Diagnostics: P0A94 (2025)
DTC P0A94: DC-DC Converter Performance Problem
General Description
The auto idle stop system equipped vehicle uses the DC-DC converter to prevent electronic accessory reset due to the 12 volt battery voltage lowering when recovering (starter motor running) from auto idle stop condition. The DC-DC converter is connected with DC_STS line for the powertrain control module (PCM) to send a voltage boost request and the local interconnect network (LIN) line for sending a diagnostic result to the PCM. When the self-diagnostic circuit in the DC-DC converter detects a failure, it is noticed to the PCM via the LIN line. If the PCM receives a DC-DC converter failure information for a set time, the PCM detects a DC-DC converter performance problem and stores a DTC.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Continuous |
| Sequence | None |
| Duration | 5 seconds or more |
| DTC Type | Two drive cycles, MIL on |
Enable Conditions
| Condition | |
|---|---|
| Vehicle | ON mode |
| Other | LIN communication is OK |
Malfunction Threshold
The PCM receives any of the following information from the DC-DC converter for at least 5 seconds.
- Internal circuit failure
- Abnormal boosting control
- Abnormal load voltage
- Abnormal input voltage
- Over load current
Possible Cause
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
- DC-DC converter +B_VST1 line open
- DC-DC converter +B_VST1 line short
- DC-DC converter +B_VST2 line open
- DC-DC converter +B_VST2 line short
- DC-DC converter DC_STS line short
- DC-DC converter IG1_ACG line open
- DC-DC converter VST_OUT1 line short
- DC-DC converter VST_OUT2 line short
- DC-DC converter PGND line open
- Electrical unit failure
- DC-DC converter failure
- PCM internal circuit failure
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC, the freeze data, and the on-board snapshot are stored.
Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, the freeze data, and the on-board snapshot can be cleared with the scan tool clear command.