P2502Charging System Voltage
- Generic OBD-II code · Powertrain
- How the car detects it
- P2502 is the general charging-system code: the engine module compares the voltage the generator actually delivers with what it has requested and finds a mismatch that it does not classify as simply too low or too high. Mazda uses it as a malfunction in the voltage produced by the generator. On 2022–2023 Mazda2 mild hybrids built in Mexico the charge lamp came on while driving; Mazda traced it to resistance at the ground terminal of the DC-DC converter under heavy current and replaced the converter with revised software. Ford lists P2502 for the 2014 BOSS 302S module. CARB lets makers pause other monitors at low or high system voltage, which is why charging faults matter for the OBD system. Directional faults are P2503 and P2504.
- What you may notice
- Charge warning lamp on while driving
- Fluctuating battery voltage, flickering lights
- Battery not fully charged
- Likely causes
- LikelyAlternator or regulator not reaching the requested voltage
- PossibleHigh resistance at ground or B+ connections (Mazda mild hybrid DC-DC converter)
- PossibleSlipping drive belt or worn tensioner
- RareBattery with internal fault distorting the charging voltage
- Repair
- Medium · Often possible to do yourself.Typical cost: €50 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.