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2021 MAZDA MAZDA3
2.0L I4•FWD•AUTOMATIC•gas
1 active safety recall on this vehicle — view recalls
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Repairs0Labor492Torque3127Fluid7DTC1132Battery1Maintenance0Recalls1
P3807moderate severityPowertrain

48V System Energy Recovery Rate Low

on 2021 Mazda Mazda3 2.0L I4 · FWD

What this code means

The 48V mild hybrid system is not recovering the expected amount of kinetic energy during deceleration and coasting events.

Symptoms

  • Mild hybrid efficiency reduced
  • 48V battery SOC not recovering during driving
  • Higher fuel consumption than expected
  • Regenerative coasting function weak
  • 48V charge indicator shows low recovery

Common causes

  • BSG belt slip during regeneration
  • 48V battery near full charge
  • BSG inverter limiting regen current
  • Drive belt tensioner weak
  • 48V battery temperature too high or low for charging

Diagnostic steps

  1. Monitor 48V regen current during deceleration
  2. Check drive belt tension and condition
  3. Read 48V battery charge acceptance limits
  4. Check BSG inverter regen current capability
  5. Monitor 48V battery temperature during regen

Repair notes

Replace drive belt and tensioner if slipping. Address 48V battery temperature management. BSG replacement if regen output is low.

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