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Home / DTC / P0562 — System Voltage Low

P0562 — System Voltage Low

Detailed page for trouble code P0562.

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Code

P0562

MERCEDES-BENZ P — Powertrain

System Voltage Low

Brand: MERCEDES-BENZ
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Weak, discharged or failing battery
  • Bad battery sensor / battery management sensor (common on Mercedes-Benz)
  • Failed or slipping alternator / voltage regulator
  • Corroded, loose or damaged battery terminals and cable connections
  • Poor chassis or engine ground straps
  • High parasitic current draw (electrical short or aftermarket equipment)

Symptoms

  • Battery/charge warning lamp illuminated
  • Dim or flickering lights and infotainment display
  • Hard or slow engine cranking, no-start or stall
  • Multiple unrelated control modules throwing faults or entering limp mode
  • Reduced performance or intermittent loss of electrical accessories
  • Stored freeze-frame data showing low system voltage during occurrence

What to check

  • Read DTCs and freeze-frame data with a capable scan tool (note battery voltage at fault time)
  • Measure battery voltage with ignition OFF, key ON (engine OFF), and while cranking using a DVM
  • Measure charging voltage with engine running at idle and at ~2000–2500 rpm
  • Inspect and clean battery terminals and cable clamp connections; check tightness
  • Inspect and measure resistance of main ground straps and engine-to-chassis grounds
  • Perform battery load test or conduct battery capacity/health test

Signal parameters

  • Battery voltage, ignition OFF: typically 12.4–12.8 V for a healthy charged battery
  • Battery voltage, ignition ON (engine OFF): ~12.2–12.8 V (depends on vehicle state)
  • Cranking voltage: should generally remain above ~9.5–10.0 V during starter engagement
  • Charging voltage, engine running: typically 13.5–14.8 V (manufacturer dependent)
  • Fault threshold: code commonly set when system voltage falls below manufacturer threshold (often ~11.5–11.8 V) or when voltage drops/stays out of range for a defined time
  • Transient dips/spikes: look for voltage dips below thresholds during accessory loads or cranking events

Diagnostic algorithm

  1. Retrieve all stored DTCs and freeze-frame data. Note reported battery voltage and operating conditions when code was set.
  2. Inspect battery condition: age, visible damage, terminal corrosion. Clean and tighten terminals.
  3. Measure static battery voltage (key off) and voltage with key on (engine off). If low, charge battery or perform battery capacity test.
  4. Perform battery load test or replace with a known-good battery to isolate battery vs charging system.
  5. Start engine and measure charging voltage at battery positive and alternator output. Verify regulator operation at idle and at increased RPM.
  6. Check voltage at vehicle control modules (ECU/BCM) to confirm wiring integrity and that modules are seeing the same supply.
  7. Inspect and test main ground straps and battery negative to chassis/engine connections; repair/replace as needed.
  8. Check for parasitic current draw with vehicle asleep. Isolate circuits by removing fuses to locate excessive drain.
  9. Test alternator diodes and ripple with an oscilloscope if intermittent drops are suspected.
  10. If equipped, verify battery sensor readings and wiring; replace or recalibrate sensor if faulty.
  11. Repair identified wiring, connectors, fuses, or charging components. Clear codes, then perform functional test drive under the conditions that previously set the code.
  12. If code returns after electrical system is confirmed healthy, consider module-level diagnostics (BCM/ECU supply circuits) with manufacturer service information.

Likely causes

  • Battery state of charge or battery health (weak cell, high internal resistance)
  • Loose/corroded cable terminals or poor ground connection
  • Alternator/voltage regulator not maintaining charge under load
  • Faulty battery sensor (on Mercedes-Benz battery management systems)

Fault status

⚠️ Status
System voltage below expected threshold detected by control module(s). Possible causes include weak battery, charging system failure, poor connections, parasitic drain or faulty battery sensor. Inspect battery, charging system and main supply/ground circuits.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours
856

Browse 856 MERCEDES-BENZ manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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