What this code means
P0A94 may indicate that the PCM is seeing possible performance or failure information from the DC-DC converter system.
What the vehicle may do
- The vehicle may display warning lights.
- Auto idle stop may not operate normally.
- The low-voltage electrical system may show symptoms if converter operation is affected.
Possible fault areas
- Possible DC-DC converter concern
- Possible power or ground circuit concern
- Possible output circuit concern
- Possible wiring or connector concern
- Possible PCM-side concern
- Possible aftermarket load connected to converter output circuits
Diagnostic path
Opening and first checks
Today we’re looking at P0A94 on a Honda CR-V with the turbo gas engine. In plain terms, this code points to a possible DC-DC converter performance problem. The vehicle may show warning lights, may have low-voltage electrical system symptoms, and auto idle stop may not behave normally. Broadly, the fault area can be the converter itself, its power and ground circuits, its output circuits, related wiring, or the PCM side of the system. Before troubleshooting, follow a structured diagnostic approach, and if another related code is present, check what that code means first before chasing P0A94 by itself. The PCM sets this code when it receives DC-DC converter failure information, so the first job is to separate a real circuit problem from a converter or control-side problem. Use the failure conditions and the way the vehicle is acting to narrow the inspection path instead of testing blindly.
Use scan data to choose the path
Next, look at the HDS data item for DC-DC Converter Cst Error. That value decides which direction you go. If the value shows Malfunction, use the external-circuit path first. If it shows Normal, move to the output and internal converter checks. For confirmation, test-drive the vehicle and stop the engine using auto idle stop, so you are working around the same type of condition that can bring the fault back.
Path A: DC_STS, power, and ground checks
On the external-circuit path, do not unplug the PCM connector cold. Before disconnecting it, jump the SCS line with the HDS and wait more than 1 minute. Then disconnect DC-DC converter connector A, the 3P connector, and PCM connector A, the 50P connector. Check the DC_STS circuit for a short to ground with IG Mode OFF. A normal result is more than 1 MΩ. If that result is abnormal, treat it as a circuit problem. The exact meter hookup and connector terminal identification need to be confirmed before testing; do not guess at the pins. After that, disconnect DC-DC converter connector B, the 5P connector, and check the +B_I/S, +B_I/S2, and ground circuits. With IG Mode OFF, the +B_I/S circuit should have 12 V battery voltage, the +B_I/S2 circuit should have 12 V battery voltage, and the ground open-wire check should be less than 1 Ω. If any of those are abnormal, the problem is in the circuit. If the power-supply side of that check is abnormal, continue with power-supply testing to locate the failure.
Path B: output circuit check
On the Normal Cst Error path, start by looking at the DC-DC converter output circuits. First, check whether any aftermarket equipment is tied into the DCDC_OUT1 or DCDC_OUT2 circuits. This check assumes the external circuit is normal. Turn the vehicle to the ON mode, then watch HDS DC-DC Converter Output Error 1 and Output Error 2. Both should read Normal. If either output check is abnormal, call it a DC-DC converter output-circuit problem. If the output circuit checks normal on this path, replace the DC-DC converter. This output check can be run early because it covers multiple inspection items, but if it fails, you still have to break the system down and test the individual items to find exactly what failed.
Internal converter check, known-good check, and PCM call
For the internal converter side, the precondition is the same: the external circuit needs to be normal. Turn the vehicle to the ON mode and check these HDS items together: DC-DC Converter Cst Error, Input Error 1, Input Error 2, Output Error 1, and Output Error 2. All of them should be Normal. If that group is normal, the fault points toward the DC-DC converter. If that group is abnormal, the problem points toward other related components. Like the output check, this internal scan-data check can be used early, but a fail still has to be broken back down into the individual related checks. There is no direct bench-style check here for the converter itself, so the diagnosis is done through related components and, when needed, a known-good DC-DC converter. Install the known-good converter and try to reproduce the failure. If the failure is reproduced, keep looking at other related components. If the symptom or DTC goes away, the DC-DC converter must be faulty. If the other inspection items have all shown normal and nothing else is left, the remaining call is a PCM problem.
Takeaway
The takeaway is simple: do not make P0A94 a converter-only diagnosis. Use the scan data to choose the path, prove the power, ground, status, and output circuits first, and only then make the call on the DC-DC converter or PCM. For more diagnostic training, visit stepdiagnostics.com.
Final check
This diagnosis is about separating external circuit issues from possible DC-DC converter or PCM-related faults before making a final call.
For more guided automotive diagnostics, visit STEP Diagnostics.
