P2502 on 2014 Mazda Mazda3 (s Grand Touring) — Charging System Voltage
1 vehicles · 1 makes
How to diagnose and fix P2502: 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. Applies only to 2014 Mazda3 vehicles equipped with i-ELOOP.
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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P2502 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 P2502 mean?
P2502 stands for "Charging System Voltage." A generic charging-system fault: the PCM has determined that charging-system voltage is outside the normal operating window (roughly 13.5–14.8 V) but cannot specifically classify it as only high or only low. It indicates the alternator/regulator output or the sensing of that output is faulty.
What are the most common causes of P2502?
The most common causes of P2502 are: Failing alternator or voltage regulator, Worn alternator brushes or slip rings, Loose, corroded, or undersized battery/charging cables, Bad ground between engine and chassis/battery, Damaged charging-system sense wiring. The specific cause varies by vehicle.
How much does it cost to fix P2502?
Repair costs vary widely depending on the root cause and vehicle.
Which vehicles are affected by P2502?
Au7o has documented P2502 across 1 vehicle models from 1 manufacturers: Mazda.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.