P0CA2: DC/DC Converter Step Down Voltage Performance

P0CA2 means the step-down function of the DC/DC converter, which brings high-voltage battery power down to the 12 V network, is not working correctly. GM's 2013 eAssist table 13OBDG05C uses it for a shoot-through fault inside the 14 volt power module: if the module detects a failed silicon power switch, a single 25 ms detection at 9 to 32 V sets the code as Type A, so the MIL lights on the first trip. Documents GM supplied to NHTSA in recall query RQ13-003 on the 2013 Malibu mild hybrid show P0CA2 in dealer cases together with P0562 for low system voltage, power pack replacements, and engineering reviews of returned parts with no fault found. P0CA3 is the step-up counterpart. Without the converter the 12 V battery drains.

High severity. Can I keep driving?If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

Symptoms

Check-engine lamp on the first trip, often with a charging warning
Falling 12 V voltage, low-voltage codes such as P0562
Hybrid assistance or auto-stop unavailable

Most likely causes

Failed power semiconductor in the converter's step-down stage
Internal fault of the power module or power pack assembly
Spurious detection without a hardware fault, for example after supply dips

What to check, in order

Start with the simplest. You can tick off each step.

Read the codes with a hybrid-compatible scanner and write down the freeze frame data
Compare the reading with other engine data while varying the engine speed.
Make sure the battery cooling air intake is clean
Check the 12 V auxiliary battery, which can also trigger warnings
Leave any high-voltage measurements to a specialized repair shop

Good to know

It can trigger limp mode.
It affects emissions.

What each character of P0CA2 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
C: Subsystem depends on the code range
A2: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0CA2?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0CA2?

The most common causes are: failed power semiconductor in the converter's step-down stage; internal fault of the power module or power pack assembly; spurious detection without a hardware fault, for example after supply dips.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.