P0A94: DC-DC converter boost response during i-stop operation

P0A94 describes DC-DC converter performance. In this SKYACTIV-G application, Mazda monitors a converter that boosts the electrical supply to stabilize vehicle devices during an i-stop restart.

A response fault, not just a voltage reading

The PCM can detect an internal-malfunction message through LIN communication or a converter response that does not satisfy its boost request. The page's translated determination text uses “pressure increase”; its functional explanation makes clear that the subject is electrical voltage boosting. No fuel-pressure diagnosis follows from this wording.

The converter may report a restricted boost period or fail to boost after a command. Mazda disables i-stop engine stopping, but the code alone does not prove the converter hardware has failed. A weak battery, damaged power feed, faulty signal wiring or poor connector can affect the same exchange.

How the procedure narrows the cause

Battery inspection precedes converter replacement. The sequence then evaluates the converter supply, both ends of the connection and the signal circuit for grounding faults, power shorts or opens. Communication faults are considered before relying on the control response.

A repeatability test must include the relevant function: Mazda starts the engine and allows an i-stop stop after clearing the stored record. Merely idling an engine that never enters i-stop does not reproduce the specified sequence. Confirmation combines that operating event with another DTC check, using the applicable vehicle procedure and safe workshop conditions.

Documented application

Mazda3 workshop manual 01/2019 onward, d9n1-1a-22d_ver10; PCM (SKYACTIV-G). Verify exact vehicle specification; this is a Mazda application example. Mazda factory diagnostic page, mirrored by CHARM.