P0562 on Mercedes-Benz: How to Diagnose & Fix
System Voltage Low
6 Mercedes-Benz models · 6 documented issues · 1 critical · $150-$900 repair
P0562 on Mercedes-Benz by model: symptoms, diagnosis and fix
The EQS experiences parasitic 12V battery drain when parked for extended periods, preventing the car from waking up or responding to the key fob. Despite having a massive high-voltage battery, the 12V system powers critical wake-up circuits and can discharge in as little as 7-10 days of inactivity.
Common Symptoms
- Car does not respond to key fob after sitting
- Unable to unlock via MBUX app
- Dashboard does not power on
- 12V battery warning before car went to sleep
How to Fix
Install the latest OTA software update which improves 12V battery management. If the car will be parked for extended periods, use a 12V trickle charger connected to the auxiliary battery. Mercedes dealers can test for excessive parasitic draw from modules failing to enter sleep mode.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- CTEK MXS 5.0 NA 12V AGM battery charger and maintainerOEMCTEK 40-206
Storage-maintenance branch for a confirmed EQS 12-volt lead-acid/AGM battery using the vehicle's approved charge points Fitment/availability: The inspected manufacturer product page identifies item 40-206 as an in-stock 12-volt lead-acid…
- Genuine Mercedes-Benz 5A battery charger with trickle-charge function A0009822921OEMMercedes-Benz A0009822921 / 000-982-29-21
Confirm VIN
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Owner tips & cautions
- TipIf you park the EQS for more than a week, connect a CTEK 12V trickle charger. The 12V battery is in the trunk — access it via the right-side trunk panel.
Mercedes communications directly support discharged 12V starter batteries and no-start conditions on both GLA generations. Communications 10157073, 10157076, 10158199 and 10158370 cover discharged batteries, no-start complaints and excessive quiescent current on earlier GLA vehicles. Communication 10217159 identifies a later bus-keepawake path in the headlamp, ALC, instrument cluster, SAM, PTCU or ESP control units, with U116000 and a software-first remedy. Communication 11018206 warns that a discharged battery does not automatically require replacement and requires onboard-data analysis to identify the cause. These records do not establish one universal relay, charging-strategy or 48V-battery cause for every 2015-2023 GLA.
Common Symptoms
- 12V state of charge and no-start condition documented
- quiescent current or bus-keepawake path identified
- battery health tested after controlled charging
How to Fix
Preserve the initial quick test and onboard electrical data before charging or disconnecting the battery. Measure quiescent current, identify any bus-keepawake control unit and follow its VIN-specific software or circuit path; separately test battery health after charging. Do not buy a battery, relay, SAM, headlamp module or 48V component from this page; the discharge cause and fitment must be established first.
Sources for this issue (1)
The EQS SUV's 12V auxiliary battery supports the entire low-voltage network - Hyperscreen, door handles, locks, and the contactors that connect the HV pack. On early X296 software the DC/DC converter did not reliably top up the 12V battery while the vehicle was parked, so cars left standing (or driven only short distances) would go completely dead: no display, no door handle presentation, no READY mode, with the 108 kWh pack sitting at 80%+ charge. Dealers commonly blame infrequent driving before diagnosing the parasitic drain or replacing the battery.
Common Symptoms
- Vehicle completely dead after sitting overnight or for a few days
- Hyperscreen dark, no response from any control
- Door handles do not present and doors will not unlock
- Cascade of unrelated warning messages before the failure
- No READY mode despite high HV state of charge
How to Fix
Have all outstanding software updates applied (the DC/DC top-up behavior was addressed by updates), then load-test and replace the 12V AGM auxiliary battery if it is weak. Mercedes advises against conventional jump-starting; the underhood positive jump terminal under the red cap plus chassis ground is the documented emergency method, and a fully dead car normally needs a flatbed. Owners who park for long periods should use a maintainer on the 12V terminals.
Sources for this issue (3)
Mercedes' current electronic architecture (shared across the C192 AMG GT, W206 C-Class, X254 GLC, and EQE/EQS) has documented 12V battery drain complaints from control modules not sleeping properly — typically the telematics / mbrace head unit polling cellular at idle. On the AMG GT specifically, there's no model-specific TSB yet, but the same root cause applies: cars left parked for 1-2+ weeks may need a jump-start, and battery management warnings can appear on the cluster. The W206 has a TSB (LI54.10-P-076820); EQE/EQS got a 2024 software recall (24V-372). Typical remedy on AMG GT is a software update at the dealer or, if the battery has been damaged by repeated deep discharge, replacement (~$400-600 for the AGM unit). Most cases are nuisance-level; severity downgraded from medium to low for that reason.
Common Symptoms
- Dead battery after sitting
- No-start or click/no crank
- Low voltage warnings
- Mercedes me app offline
- Random electrical faults after jump-start
How to Fix
Perform a parasitic draw test after the vehicle times out, then scan all body, telematics, and gateway modules for wake-up events or software faults. Dealers often address this with software updates, battery testing/replacement, and in some cases replacement of a module that remains awake. Owners who store the car or drive infrequently often use a maintainer to prevent repeat discharge while the root cause is being resolved.
What you need to diagnose it
The fix here starts with a test, not a part — which repair you need depends on what the test finds.
UNI-T UT210E Low-Current DC Clamp Meter
1 mA resolution on the 2 A range — a 0.1 A meter reads a 50 mA drain as zero
$40–$70View
As an Amazon Associate, we earn from qualifying purchases. Prices are approximate and may vary.
Testing and isolating the fault is DIY work. Replacing or reprogramming a control module is not — most are VIN-programmed, so a new one does nothing until a shop codes it to your car. Check for an open recall or service bulletin before buying anything.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- CTEK MXS 5.0 NA 12-volt AGM-compatible charger/maintainerOEMCTEK 40-206 MXS 5.0 NA
Storage maintenance for a verified 12-volt lead-acid/AGM battery while the root cause is diagnosed Fitment/availability: The inspected U.S. manufacturer page identifies item 40-206 for 12-volt lead-acid batteries including AGM/EFB, 1.2-1…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
On NCV3 Sprinters the heavy charging cable runs from the alternator to the starter stud and then on to the battery, with a fusible link spliced into the harness (the so-called Y-cable). The splice is covered only by heat-shrink that is not truly watertight. Under sustained high-current charging the splice heats up, the shrink tube splits, and road salt and moisture attack the exposed conductor. The link corrodes and its resistance climbs, so the battery never sees full alternator output. Owners report chronic low system voltage, weak cranking, batteries that die early, and alternators condemned and replaced when the cable was the actual fault. Because the fault is resistive rather than open, it often throws no code and voltage measured at the alternator looks fine while voltage at the battery is a volt or more lower.
Common Symptoms
- Low charging voltage at the battery
- Slow or weak cranking
- Repeat premature battery failure
- Repeat alternator replacement that does not fix the charging fault
- Battery warning light intermittently
How to Fix
Diagnose by measuring voltage at the alternator B+ post and at the battery positive post with the engine running and a load applied - more than roughly 0.3V of difference means the cable/fusible link is the problem. Replace the Y-cable harness with the updated Mercedes part rather than splicing, and clean and re-torque the starter stud and battery terminals. Do not replace the alternator or battery until the cable voltage drop has been measured; many owners have replaced both twice before finding the corroded link.
Sources for this issue (3)
The EQE keeps its 12V AGM battery topped up from the HV pack through the DC/DC converter, but only when the vehicle's control units are allowed to sleep. Owners report telematics and comfort modules that never enter sleep — triggered by scheduled departure/preconditioning times, Mercedes me app polling, or an aftermarket OBD dongle — which drains the 12V overnight and, in the worst pattern, makes the HV pack cycle repeatedly to nurse a weak 12V. (Owner speculation - no manufacturer bulletin confirms an OBD dongle or app polling as the root cause.) The result is roughly 1-2%/day standing loss in owner reports (against a normal figure well under 1%) or a car that is simply dead in the morning with a 12V warning. A weak 12V also cascades: door handles won't present, the charge flap won't unlock, MBUX won't boot.
Common Symptoms
- "12V battery low" or "Battery malfunction" message
- Car dead / no response to key after sitting
- 5-10% HV state-of-charge lost per day while parked
- Door handles do not present
- Charge flap will not unlock
- Multiple random warning messages on startup
How to Fix
First, remove any aftermarket OBD dongle and turn off scheduled departure times, pre-entry climate and seat preconditioning in MBUX / Mercedes me. (Owner speculation - no manufacturer bulletin confirms an OBD dongle or app polling as the root cause.) Have the dealer run a quiescent-current (parasitic draw) test with XENTRY to find the module that isn't sleeping and apply the current control-unit software. If the AGM itself is degraded, replace it — the EQE 12V AGM must be registered/coded to the battery-monitoring sensor with XENTRY or the DC/DC charging strategy stays wrong and the new battery dies too.
Sources for this issue (3)
P0562 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 P0562 mean on a Mercedes-Benz?
P0562 stands for "System Voltage Low." P0562 means the engine computer detected that the vehicle's system (battery/charging) voltage is too low for normal operation. The computer constantly monitors charging-system voltage because nearly every sensor, injector, and module depends on a stable supply; sustained low voltage can cause erratic behavior and other false codes. This is most often a charging or battery problem — the alternator isn't keeping up, the battery is weak, or there's resistance in the cables/grounds. You may notice dim lights, slow cranking, or multiple unrelated warning lights. On Mercedes-Benz it is documented across 6 models: EQS, GLA, EQS SUV, AMG GT, Sprinter, EQE.
What are the most common causes of P0562?
The most common causes of P0562 are: Failing alternator or worn alternator brushes/regulator, Weak, old, or discharged battery, Corroded, loose, or damaged battery cables and terminals, Bad engine or chassis ground connections, Slipping, glazed, or broken serpentine/drive belt, High resistance in charging system wiring or fusible link, Faulty PCM voltage reference or charging-system control. The specific cause varies by vehicle.
How much does it cost to fix P0562 on a Mercedes-Benz?
Published repair estimates on Mercedes-Benz range from $150 to $900 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0562 on a different make?
View P0562 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.