P1794 on 2014 Mazda Mazda3 (s Grand Touring) — Capacitor (i-ELOOP) System Malfunction
1 vehicles · 1 makes
How to diagnose and fix P1794: most-reported vehicles
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Mazda Mazda3 · 2014–2014
On some 2014 Mazda3s with the 2.5L engine and i-ELOOP, the PCM can wrongly decide the i-ELOOP capacitor has failed when the generator belt gets wet and slips in heavy rain or deep puddles. It then stops the charging system and shows the charging-system warning. If driving continues, the battery drains, the check engine light comes on and acceleration drops. Steering assist, the wipers and finally the engine can then stop. Mazda recall 7314D (NHTSA 14V-173) covers 2014 Mazda3 2.5 i-ELOOP cars built June 12 to December 18, 2013. Separately, Mazda bulletin 01-001/14 covers 2014 Mazda3s with i-ELOOP built before June 25, 2014 that show "i-ELOOP Malfunction" with the master and charging warning lights and DTC P1794:00. Only 2014 Mazda3 vehicles equipped with i-ELOOP are affected.
Common Symptoms
- Charging-system warning light after driving in heavy rain or deep puddles
- "i-ELOOP Malfunction" message with the master warning light
- DTC P1794:00 stored
- Battery drains
- Check engine light comes on
- Reduced acceleration
- Loss of steering assist and wipers
- Engine stalls
How to Fix
Have a Mazda dealer check the VIN for recall 7314D (NHTSA 14V-173). The free remedy is PCM reprogramming so that the PCM correctly identifies the capacitor's condition. For a qualifying 2014 Mazda3 with P1794:00, bulletin 01-001/14 calls for a PCM calibration update once the technician confirms the qualifying data. If the car does not qualify, the bulletin sends the technician to the workshop-manual P1794 diagnosis. Normal warranty rules apply to the bulletin; it is not a recall or a promise of free repair. Charging-system diagnosis is technician work.
Call to confirm they can assess your vehicle and perform the stated work. Search results do not confirm qualification, eligibility or coverage.
Sources for this issue (5)
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P1794 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P1794 mean?
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.
What are the most common causes of P1794?
The most common causes of P1794 are: 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. The specific cause varies by vehicle.
How much does it cost to fix P1794?
Repair costs vary widely depending on the root cause and vehicle.
Which vehicles are affected by P1794?
Au7o has documented P1794 across 1 vehicle models from 1 manufacturers: Mazda.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.