P1794 on Mazda
Capacitor (i-ELOOP) System Malfunction
P1794 on Mazda vehicles indicates capacitor (i-eloop) system malfunction. Au7o has documented this code across 1 Mazda model — most commonly on Mazda3. The PCM monitors the i-ELOOP electric double-layer capacitor and the DC-DC converter that steps its stored voltage down to the 12-volt system. P1794 sets when the capacitor circuit does not charge, discharge, or report correctly - most commonly an open or high-resistance path in the signal harness between the DC-DC converter and the capacitor. Mazda documented that an oxide film can form on the terminals of that signal-harness connector, which is a key root cause of this code. Typical repair costs on Mazda range from $600 to $1,800, depending on the specific model and root cause.
Common Causes of P1794
- •Oxide film on the signal-harness connector terminals between the DC-DC converter and the capacitor (Mazda-documented cause)
- •Failed i-ELOOP capacitor assembly with an internal open circuit
- •Failed DC-DC converter
- •Open or damaged wiring between the capacitor, DC-DC converter, and alternator
- •Poor ground or corroded connector terminals
P1794 on Mazda by Model
Mazda Mazda3(1 issue)
- 2014-2018 Mazda3 i-ELOOP Capacitor / DC-DC Converter Failure - Charging System Warning and P17942014-2018
On i-ELOOP equipped BM/BN Mazda3s, regenerative braking energy is stored in an electric double-layer capacitor mounted in the engine bay and fed back to the 12V system through a DC-DC converter. The capacitor develops an internal open circuit, or the DC-DC converter fails, and the PCM sets P1794 with an 'i-ELOOP Malfunction' message in the instrument cluster plus the master warning and battery/charging lights. Because the DC-DC converter also supplies the 12V system when i-ELOOP is active, a failure can leave the alternator carrying everything, run the battery down and disable i-stop. Mazda also issued a service bulletin for false i-ELOOP faults triggered when the accessory belt gets wet in heavy rain or deep water, so a wet-weather-only warning is not necessarily a dead capacitor.
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View P1794 across all makes →Frequently Asked Questions
What does P1794 mean on Mazda?▼
P1794 stands for "Capacitor (i-ELOOP) System Malfunction." The PCM monitors the i-ELOOP electric double-layer capacitor and the DC-DC converter that steps its stored voltage down to the 12-volt system. P1794 sets when the capacitor circuit does not charge, discharge, or report correctly - most commonly an open or high-resistance path in the signal harness between the DC-DC converter and the capacitor. Mazda documented that an oxide film can form on the terminals of that signal-harness connector, which is a key root cause of this code. On Mazda specifically, this code is documented across 1 model.
What causes P1794 on Mazda vehicles?▼
Common causes on Mazda: Oxide film on the signal-harness connector terminals between the DC-DC converter and the capacitor (Mazda-documented cause), Failed i-ELOOP capacitor assembly with an internal open circuit, Failed DC-DC converter, Open or damaged wiring between the capacitor, DC-DC converter, and alternator, Poor ground or corroded connector terminals. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P1794 on a Mazda?▼
Repair costs on Mazda range from $600 to $1,800, depending on the specific model and root cause.
Which Mazda models have P1794 documented?▼
Au7o has documented P1794 on 1 Mazda model: Mazda3.